sysstats: refresh cpuFreq every 3rd tick instead of every tick

/proc/cpuinfo is regenerated in full by the kernel on every read and
its cost grows with core count, making it the priciest per-tick read.
Bar frequency display doesn't need 1 Hz precision.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

services/SysStats.qml

@@ -52,6 +52,12 @@ Singleton {
     // poll interval in seconds
     readonly property int interval: 1
 
+    // cpuFreq comes from /proc/cpuinfo, which the kernel regenerates in full on
+    // every read (cost grows with core count) — the priciest per-tick read here.
+    // Frequency on a status bar doesn't need 1 Hz precision, so only refresh it
+    // every Nth tick instead of on the CPU%/mem hot path.
+    readonly property int freqEveryTicks: 3
+
     // discovered sysfs paths (filled once by discover.sh)
     property string tempPath: ""
     property string batPath: ""
@@ -271,15 +277,17 @@ Singleton {
     }
 
     function _tickOnce() {
+        const doFreq = root._tick % root.freqEveryTicks === 0;
+
         statView.reload();
-        cpuInfoView.reload();
+        if (doFreq) cpuInfoView.reload();
         memView.reload();
         routeView.reload();
         if (root.tempPath) tempView.reload();
         if (root.batPath) { batCapView.reload(); batStatusView.reload(); }
 
         _parseCpu();
-        _parseFreq();
+        if (doFreq) _parseFreq();
         _parseMem();
         _parseTemp();
         _parseBattery();