diff --git a/include/ss/common.hpp b/include/ss/common.hpp
index 7531e29..bc6dd6a 100644
--- a/include/ss/common.hpp
+++ b/include/ss/common.hpp
@@ -25,60 +25,4 @@ inline void assert_throw_on_error_not_defined() {
                                  "'throw_on_error' is enabled");
 }
 
-#if __unix__
-inline ssize_t get_line(char** lineptr, size_t* n, FILE* stream) {
-    return getline(lineptr, n, stream);
-}
-#else
-using ssize_t = int64_t;
-inline ssize_t get_line(char** lineptr, size_t* n, FILE* stream) {
-    size_t pos;
-    int c;
-
-    if (lineptr == nullptr || stream == nullptr || n == nullptr) {
-        errno = EINVAL;
-        return -1;
-    }
-
-    c = getc(stream);
-    if (c == EOF) {
-        return -1;
-    }
-
-    if (*lineptr == nullptr) {
-        *lineptr = static_cast<char*>(malloc(128));
-        if (*lineptr == nullptr) {
-            return -1;
-        }
-        *n = 128;
-    }
-
-    pos = 0;
-    while (c != EOF) {
-        if (pos + 1 >= *n) {
-            size_t new_size = *n + (*n >> 2);
-            if (new_size < 128) {
-                new_size = 128;
-            }
-            char* new_ptr = static_cast<char*>(
-                realloc(static_cast<void*>(*lineptr), new_size));
-            if (new_ptr == nullptr) {
-                return -1;
-            }
-            *n = new_size;
-            *lineptr = new_ptr;
-        }
-
-        (*lineptr)[pos++] = c;
-        if (c == '\n') {
-            break;
-        }
-        c = getc(stream);
-    }
-
-    (*lineptr)[pos] = '\0';
-    return pos;
-}
-#endif
-
 } /* ss */
diff --git a/include/ss/parser.hpp b/include/ss/parser.hpp
index db80dd3..2136a9a 100644
--- a/include/ss/parser.hpp
+++ b/include/ss/parser.hpp
@@ -1,5 +1,12 @@
 #pragma once
 
+// TODO remove or rename
+#define likely(x) __builtin_expect(!!(x), 1)
+#define unlikely(x) __builtin_expect(!!(x), 0)
+
+#define U_IF(OP) if (unlikely(OP))
+#define L_IF(OP) if (likely(OP))
+
 #include "common.hpp"
 #include "converter.hpp"
 #include "exception.hpp"
@@ -36,11 +43,12 @@ public:
            const std::string& delim = ss::default_delimiter)
         : file_name_{file_name}, reader_{file_name_, delim} {
         if (reader_.file_) {
-            read_line();
+            // read_line();
             if constexpr (ignore_header) {
                 ignore_next();
             } else {
-                raw_header_ = reader_.get_buffer();
+                // TODO handle
+                // raw_header_ = reader_.get_buffer();
             }
         } else {
             handle_error_file_not_open();
@@ -84,34 +92,11 @@ public:
     }
 
     size_t line() const {
-        return reader_.line_number_ > 1 ? reader_.line_number_ - 1
-                                        : reader_.line_number_;
+        return reader_.line_number_;
     }
 
     template <typename T, typename... Ts>
     no_void_validator_tup_t<T, Ts...> get_next() {
-        std::optional<std::string> error;
-
-        if (!eof_) {
-            if constexpr (throw_on_error) {
-                try {
-                    reader_.parse();
-                } catch (const ss::exception& e) {
-                    read_line();
-                    decorate_rethrow(e);
-                }
-            } else {
-                reader_.parse();
-            }
-        }
-
-        reader_.update();
-        if (!reader_.converter_.valid()) {
-            handle_error_invalid_conversion();
-            read_line();
-            return {};
-        }
-
         clear_error();
 
         if (eof_) {
@@ -121,22 +106,24 @@ public:
 
         if constexpr (throw_on_error) {
             try {
-                auto value = reader_.converter_.template convert<T, Ts...>();
                 read_line();
-                return value;
+                return reader_.converter_.template convert<T, Ts...>(
+                    reader_.split_data_);
             } catch (const ss::exception& e) {
-                read_line();
                 decorate_rethrow(e);
             }
         }
 
-        auto value = reader_.converter_.template convert<T, Ts...>();
+        read_line();
+        // TODO check valid read
+
+        auto value =
+            reader_.converter_.template convert<T, Ts...>(reader_.split_data_);
 
         if (!reader_.converter_.valid()) {
             handle_error_invalid_conversion();
         }
 
-        read_line();
         return value;
     }
 
@@ -189,8 +176,6 @@ public:
         }
 
         reader_.converter_.set_column_mapping(column_mappings, header_.size());
-        reader_.next_line_converter_.set_column_mapping(column_mappings,
-                                                        header_.size());
 
         if (line() == 1) {
             ignore_next();
@@ -636,258 +621,215 @@ private:
         eof_ = !reader_.read_next();
     }
 
+    ////////////////
+    // new reader
+    ////////////////
     struct reader {
-        reader(const std::string& file_name_, const std::string& delim)
-            : delim_{delim}, file_{fopen(file_name_.c_str(), "rb")} {
-        }
+        reader(const reader& other) = delete;
+        reader& operator=(const reader& other) = delete;
 
+        // TODO update
         reader(reader&& other)
-            : buffer_{other.buffer_},
-              next_line_buffer_{other.next_line_buffer_},
-              helper_buffer_{other.helper_buffer_}, converter_{std::move(
-                                                        other.converter_)},
-              next_line_converter_{std::move(other.next_line_converter_)},
-              buffer_size_{other.buffer_size_},
-              next_line_buffer_size_{other.next_line_buffer_size_},
-              helper_size_{other.helper_size_}, delim_{std::move(other.delim_)},
-              file_{other.file_}, crlf_{other.crlf_},
-              line_number_{other.line_number_}, next_line_size_{
-                                                    other.next_line_size_} {
-            other.buffer_ = nullptr;
-            other.next_line_buffer_ = nullptr;
-            other.helper_buffer_ = nullptr;
+            : delim_{std::move(other.delim_)}, file_{other.file_},
+              converter_{std::move(other.converter_)}, buff_{other.buff_},
+              line_number_{other.line_number_}, buff_size_{other.buff_size_},
+              buff_filled_{other.buff_filled_},
+              buff_processed_{other.buff_processed_},
+              delim_char_{other.delim_char_}, begin_{other.begin_},
+              curr_{other.curr_}, end_{other.end_},
+              last_read_{other.last_read_}, split_data_{
+                                                std::move(other.split_data_)} {
             other.file_ = nullptr;
+            other.buff_ = nullptr;
         }
 
         reader& operator=(reader&& other) {
             if (this != &other) {
-                buffer_ = other.buffer_;
-                next_line_buffer_ = other.next_line_buffer_;
-                helper_buffer_ = other.helper_buffer_;
-                converter_ = std::move(other.converter_);
-                next_line_converter_ = std::move(other.next_line_converter_);
-                buffer_size_ = other.buffer_size_;
-                next_line_buffer_size_ = other.next_line_buffer_size_;
-                helper_size_ = other.helper_size_;
                 delim_ = std::move(other.delim_);
                 file_ = other.file_;
-                crlf_ = other.crlf_;
+                converter_ = std::move(other.converter_);
+                buff_ = other.buff_;
                 line_number_ = other.line_number_;
-                next_line_size_ = other.next_line_size_;
+                buff_filled_ = other.buff_filled_;
+                buff_size_ = other.buff_size_;
+                buff_processed_ = other.buff_processed_;
+                delim_char_ = other.delim_char_;
+                begin_ = other.begin_;
+                curr_ = other.curr_;
+                end_ = other.end_;
+                last_read_ = other.last_read_;
+                split_data_ = std::move(other.split_data_);
 
-                other.buffer_ = nullptr;
-                other.next_line_buffer_ = nullptr;
-                other.helper_buffer_ = nullptr;
                 other.file_ = nullptr;
+                other.buff_ = nullptr;
             }
-
             return *this;
         }
 
+        reader(const std::string& file_name, const std::string& delim)
+            : delim_{delim} {
+
+            // TODO update
+            delim_char_ = delim_.at(0);
+
+            // TODO check file
+            file_ = std::fopen(file_name.c_str(), "rb");
+
+            if (!file_) {
+                return;
+            }
+
+            // TODO check buff_
+            buff_ = static_cast<char*>(std::malloc(buff_size_));
+
+            // TODO check buff_filled
+            buff_filled_ = std::fread(buff_, 1, buff_size_, file_);
+
+            if (buff_filled_ != buff_size_) {
+                last_read_ = true;
+            }
+
+            // TODO handle differently
+            if (buff_filled_ == 0 || (buff_filled_ == 1 && buff_[0] == '\n') ||
+                (buff_filled_ == 2 && buff_[0] == '\r' && buff_[1] == '\n')) {
+                free(file_);
+                file_ = nullptr;
+            }
+
+            begin_ = buff_;
+            curr_ = buff_;
+            end_ = buff_ + buff_filled_;
+        }
+
         ~reader() {
-            free(buffer_);
-            free(next_line_buffer_);
-            free(helper_buffer_);
+            free(buff_);
 
             if (file_) {
                 fclose(file_);
             }
         }
 
-        reader() = delete;
-        reader(const reader& other) = delete;
-        reader& operator=(const reader& other) = delete;
+        void shift_read_next() {
+            buff_filled_ -= buff_processed_;
+
+            // shift back data that is not processed
+            memcpy(buff_, buff_ + buff_processed_, buff_filled_);
+
+            // read data to fill the rest of the buffer
+            buff_filled_ +=
+                fread(buff_ + buff_filled_, 1, buff_processed_, file_);
+        }
+
+        void handle_buffer_end_reached() {
+            buff_size_ *= 8;
+
+            // TODO handle NULL
+            buff_ = static_cast<char*>(std::realloc(buff_, buff_size_));
+
+            // fill the rest of the buffer
+            buff_filled_ += fread(buff_ + buff_filled_, 1,
+                                  buff_size_ - buff_filled_, file_);
+
+            if (buff_filled_ != buff_size_) {
+                last_read_ = true;
+            }
+        };
 
         // read next line each time in order to set eof_
         bool read_next() {
-            next_line_converter_.clear_error();
-            ssize_t ssize = 0;
-            size_t size = 0;
-            while (size == 0) {
-                ++line_number_;
-                if (next_line_buffer_size_ > 0) {
-                    next_line_buffer_[0] = '\0';
+            // TODO update division value
+            if (buff_processed_ > buff_filled_ / 2) {
+                if (!last_read_) {
+                    shift_read_next();
+
+                    if (buff_filled_ != buff_size_) {
+                        last_read_ = true;
+                    }
+
+                    curr_ = buff_;
+                    end_ = buff_ + buff_filled_;
                 }
-                ssize = get_line(&next_line_buffer_, &next_line_buffer_size_,
-                                 file_);
+            }
 
-                if (ssize == -1) {
-                    return false;
-                }
+            split_data_.clear();
+            begin_ = curr_;
 
-                size = remove_eol(next_line_buffer_, ssize);
-
-                if constexpr (!ignore_empty) {
+            while (true) {
+                if (*curr_ == '\n') {
+                    split_data_.emplace_back(begin_, curr_);
                     break;
                 }
-            }
 
-            next_line_size_ = size;
-            return true;
-        }
+                if (*curr_ == '\r' && *(curr_ + 1) == '\n') {
+                    split_data_.emplace_back(begin_, curr_);
+                    ++curr_;
+                    break;
+                }
 
-        void parse() {
-            size_t limit = 0;
+                if (*curr_ == delim_char_) {
+                    split_data_.emplace_back(begin_, curr_);
+                    begin_ = curr_ + 1;
+                }
 
-            if constexpr (escaped_multiline_enabled) {
-                while (escaped_eol(next_line_size_)) {
-                    if (multiline_limit_reached(limit)) {
-                        return;
+                ++curr_;
+
+                if (curr_ == end_) {
+                    auto old_buff = buff_;
+
+                    if (last_read_) {
+                        // TODO handle
+                        throw std::string{"no new line at eof"};
                     }
 
-                    if (!append_next_line_to_buffer(next_line_buffer_,
-                                                    next_line_size_)) {
-                        next_line_converter_.handle_error_unterminated_escape();
-                        return;
+                    handle_buffer_end_reached();
+                    end_ = buff_ + buff_filled_;
+
+                    for (auto& [begin, end] : split_data_) {
+                        begin = begin - old_buff + buff_;
+                        end = end - old_buff + buff_;
                     }
+
+                    begin_ = begin_ - old_buff + buff_;
+                    curr_ = curr_ - old_buff + buff_;
                 }
             }
 
-            next_line_converter_.split(next_line_buffer_, delim_);
+            ++curr_;
+            buff_processed_ = curr_ - buff_;
 
-            if constexpr (quoted_multiline_enabled) {
-                while (unterminated_quote()) {
-                    next_line_size_ -= next_line_converter_.size_shifted();
+            // TODO check where to put this
+            ++line_number_;
 
-                    if (multiline_limit_reached(limit)) {
-                        return;
-                    }
-
-                    if (!append_next_line_to_buffer(next_line_buffer_,
-                                                    next_line_size_)) {
-                        next_line_converter_.handle_error_unterminated_quote();
-                        return;
-                    }
-
-                    if constexpr (escaped_multiline_enabled) {
-                        while (escaped_eol(next_line_size_)) {
-                            if (multiline_limit_reached(limit)) {
-                                return;
-                            }
-
-                            if (!append_next_line_to_buffer(next_line_buffer_,
-                                                            next_line_size_)) {
-                                next_line_converter_
-                                    .handle_error_unterminated_escape();
-                                return;
-                            }
-                        }
-                    }
-
-                    next_line_converter_.resplit(next_line_buffer_,
-                                                 next_line_size_, delim_);
-                }
-            }
-        }
-
-        void update() {
-            std::swap(buffer_, next_line_buffer_);
-            std::swap(buffer_size_, next_line_buffer_size_);
-            std::swap(converter_, next_line_converter_);
-        }
-
-        bool multiline_limit_reached(size_t& limit) {
-            if constexpr (multiline::size > 0) {
-                if (limit++ >= multiline::size) {
-                    next_line_converter_.handle_error_multiline_limit_reached();
-                    return true;
-                }
-            }
-            return false;
-        }
-
-        bool escaped_eol(size_t size) {
-            const char* curr;
-            for (curr = next_line_buffer_ + size - 1;
-                 curr >= next_line_buffer_ &&
-                 setup<Options...>::escape::match(*curr);
-                 --curr) {
-            }
-            return (next_line_buffer_ - curr + size) % 2 == 0;
-        }
-
-        bool unterminated_quote() {
-            return next_line_converter_.unterminated_quote();
-        }
-
-        void undo_remove_eol(char* buffer, size_t& string_end) {
-            if (crlf_) {
-                std::copy_n("\r\n\0", 3, buffer + string_end);
-                string_end += 2;
-            } else {
-                std::copy_n("\n\0", 2, buffer + string_end);
-                string_end += 1;
-            }
-        }
-
-        size_t remove_eol(char*& buffer, size_t ssize) {
-            size_t size = ssize - 1;
-            if (ssize >= 2 && buffer[ssize - 2] == '\r') {
-                crlf_ = true;
-                size--;
-            } else {
-                crlf_ = false;
-            }
-
-            buffer[size] = '\0';
-            return size;
-        }
-
-        void realloc_concat(char*& first, size_t& first_size,
-                            const char* const second, size_t second_size) {
-            // TODO make buffer_size an argument
-            next_line_buffer_size_ = first_size + second_size + 3;
-            auto new_first = static_cast<char*>(
-                realloc(static_cast<void*>(first), next_line_buffer_size_));
-            if (!first) {
-                throw std::bad_alloc{};
-            }
-
-            first = new_first;
-            std::copy_n(second, second_size + 1, first + first_size);
-            first_size += second_size;
-        }
-
-        bool append_next_line_to_buffer(char*& buffer, size_t& size) {
-            undo_remove_eol(buffer, size);
-
-            ssize_t next_ssize =
-                get_line(&helper_buffer_, &helper_size_, file_);
-            if (next_ssize == -1) {
+            if (last_read_ && curr_ >= end_) {
                 return false;
             }
 
-            ++line_number_;
-            size_t next_size = remove_eol(helper_buffer_, next_ssize);
-            realloc_concat(buffer, size, helper_buffer_, next_size);
             return true;
         }
 
-        std::string get_buffer() {
-            return std::string{next_line_buffer_, next_line_buffer_size_};
-        }
-
-        ////////////////
-        // members
-        ////////////////
-        char* buffer_{nullptr};
-        char* next_line_buffer_{nullptr};
-        char* helper_buffer_{nullptr};
-
-        converter<Options...> converter_;
-        converter<Options...> next_line_converter_;
-
-        size_t buffer_size_{0};
-        size_t next_line_buffer_size_{0};
-        size_t helper_size_{0};
-
-        std::string delim_;
+        std::string delim_{};
         FILE* file_{nullptr};
 
-        bool crlf_{false};
+        converter<Options...> converter_;
+        char* buff_{nullptr};
         size_t line_number_{0};
 
-        size_t next_line_size_{0};
+        // TODO set initial buffer size
+        size_t buff_size_{1};
+        size_t buff_filled_{0};
+        size_t buff_processed_{0};
+
+        // TODO update
+        char delim_char_;
+
+        // TODO move to splitter
+        char* begin_{nullptr};
+        char* curr_{nullptr};
+        char* end_{nullptr};
+
+        bool last_read_{false};
+
+        split_data split_data_;
     };
 
     ////////////////