diff --git a/public/js/app.js b/public/js/app.js
index 8542f87..991dcf9 100644
--- a/public/js/app.js
+++ b/public/js/app.js
@@ -706,12 +706,12 @@
           valB = b.cpuPercent ?? 0;
           break;
         case 'mem':
-          valA = a.memTotal > 0 ? (a.memUsed / a.memTotal) : 0;
-          valB = b.memTotal > 0 ? (b.memUsed / b.memTotal) : 0;
+          valA = a.memPercent ?? 0;
+          valB = b.memPercent ?? 0;
           break;
         case 'disk':
-          valA = a.diskTotal > 0 ? (a.diskUsed / a.diskTotal) : 0;
-          valB = b.diskTotal > 0 ? (b.diskUsed / b.diskTotal) : 0;
+          valA = a.diskPercent ?? 0;
+          valB = b.diskPercent ?? 0;
           break;
         case 'netRx':
           valA = a.netRx ?? 0;
@@ -853,8 +853,8 @@
     }
 
     dom.serverTableBody.innerHTML = servers.map(server => {
-      const memPct = server.memTotal > 0 ? (server.memUsed / server.memTotal * 100) : 0;
-      const diskPct = server.diskTotal > 0 ? (server.diskUsed / server.diskTotal * 100) : 0;
+      const memPct = server.memPercent || 0;
+      const diskPct = server.diskPercent || 0;
 
       return `
         <tr data-instance="${escapeHtml(server.instance)}" data-job="${escapeHtml(server.job)}" data-source="${escapeHtml(server.source)}" style="cursor: pointer;">
@@ -943,9 +943,8 @@
     dom.detailUptime.textContent = `${days}天 ${hours}小时 ${mins}分`;
 
     // Disk Total
-    const totalDiskSize = (data.partitions || []).reduce((sum, p) => sum + (p.size || 0), 0);
     if (dom.detailDiskTotal) {
-        dom.detailDiskTotal.textContent = formatBytes(totalDiskSize);
+        dom.detailDiskTotal.textContent = formatBytes(data.totalDiskSize || 0);
     }
 
     // Define metrics to show
@@ -1118,15 +1117,8 @@
       if (!res.ok) throw new Error('Query failed');
       const data = await res.json();
 
-      if (metricKey === 'cpuBusy' && data.series) {
-        // Simplify: ONLY show total busy CPU usage (everything except idle)
-        // Since it's a percentage, 100 - idle is the total busy percentage
-        data.values = data.series.idle.map(idleVal => Math.max(0, 100 - idleVal));
-        data.series = null; // This tells MetricChart to draw a single line instead of stacked area
-      }
-
-      if (metricKey === 'networkTrend') {
-          const stats = calculateHistoryStats(data);
+      if (metricKey === 'networkTrend' && data.stats) {
+          const stats = data.stats;
           const summaryDiv = document.getElementById(`summary-${metricKey}`);
           if (summaryDiv) {
               summaryDiv.style.display = 'flex';
@@ -1148,38 +1140,6 @@
     }
   };
 
-  function calculateHistoryStats(data) {
-    if (!data.timestamps || data.timestamps.length < 2) {
-      return { rxTotal: 0, txTotal: 0, p95: 0, total: 0 };
-    }
-
-    const tx = data.tx || [];
-    const rx = data.rx || [];
-    const ts = data.timestamps;
-
-    let rxTotal = 0;
-    let txTotal = 0;
-
-    for (let i = 0; i < ts.length - 1; i++) {
-        // Find interval in seconds
-        const duration = (ts[i+1] - ts[i]) / 1000; 
-        // Bandwidth (B/s) * time (s) = Bytes
-        rxTotal += (rx[i] || 0) * duration;
-        txTotal += (tx[i] || 0) * duration;
-    }
-
-    // P95 calculation for TX (consistent with AreaChart)
-    const sortedTx = [...tx].sort((a, b) => a - b);
-    const p95Idx = Math.floor(sortedTx.length * 0.95);
-    const p95 = sortedTx.length > 0 ? sortedTx[p95Idx] : 0;
-
-    return {
-        rxTotal,
-        txTotal,
-        p95,
-        total: rxTotal + txTotal
-    };
-  }
 
   window.loadCustomMetricHistory = async function (metricKey, event) {
     if (event) event.stopPropagation();
diff --git a/server/prometheus-service.js b/server/prometheus-service.js
index 3ee638b..31b2c47 100644
--- a/server/prometheus-service.js
+++ b/server/prometheus-service.js
@@ -238,7 +238,9 @@ async function getOverviewMetrics(url, sourceName) {
         diskUsed: 0,
         netRx: 0,
         netTx: 0,
-        up: false
+        up: false,
+        memPercent: 0,
+        diskPercent: 0
       });
     }
     const inst = instances.get(token);
@@ -308,6 +310,9 @@ async function getOverviewMetrics(url, sourceName) {
     if (!inst.up && (inst.cpuPercent > 0 || inst.memTotal > 0)) {
       inst.up = true;
     }
+    // Calculate percentages on backend
+    inst.memPercent = inst.memTotal > 0 ? (inst.memUsed / inst.memTotal * 100) : 0;
+    inst.diskPercent = inst.diskTotal > 0 ? (inst.diskUsed / inst.diskTotal * 100) : 0;
   }
 
   const allInstancesList = Array.from(instances.values());
@@ -606,6 +611,9 @@ async function getServerDetails(baseUrl, instance, job) {
       percent: p.size > 0 ? ((p.size - p.free) / p.size * 100) : 0
   })).sort((a, b) => a.mountpoint.localeCompare(b.mountpoint));
 
+  // Calculate total disk size
+  results.totalDiskSize = results.partitions.reduce((sum, p) => sum + (p.size || 0), 0);
+
   delete results.partitions_size;
   delete results.partitions_free;
 
@@ -659,7 +667,11 @@ async function getServerHistory(baseUrl, instance, job, metric, range = '1h', st
           r.values.forEach(v => series[r.name].push(parseFloat(v[1])));
       });
 
-      return { timestamps, series };
+      // Pre-calculate busy percentage: 100 - idle
+      const idleValues = series.idle || [];
+      const busyValues = idleValues.map(idleVal => Math.max(0, 100 - idleVal));
+
+      return { timestamps, series, values: busyValues };
   }
 
   // Map metric keys to Prometheus expressions
@@ -690,7 +702,30 @@ async function getServerHistory(baseUrl, instance, job, metric, range = '1h', st
       const tx = txResult.length > 0 ? txResult[0].values.map(v => parseFloat(v[1])) : new Array(timestamps.length).fill(0);
       const rx = rxResult.length > 0 ? rxResult[0].values.map(v => parseFloat(v[1])) : new Array(timestamps.length).fill(0);
       
-      return { timestamps, tx, rx };
+      // Calculate statistics on backend
+      let rxTotal = 0;
+      let txTotal = 0;
+      for (let i = 0; i < timestamps.length - 1; i++) {
+          const duration = (timestamps[i+1] - timestamps[i]) / 1000;
+          rxTotal += (rx[i] || 0) * duration;
+          txTotal += (tx[i] || 0) * duration;
+      }
+
+      const sortedTx = [...tx].sort((a, b) => a - b);
+      const p95Idx = Math.floor(sortedTx.length * 0.95);
+      const p95 = sortedTx.length > 0 ? sortedTx[p95Idx] : 0;
+
+      return { 
+          timestamps, 
+          tx, 
+          rx,
+          stats: {
+              rxTotal,
+              txTotal,
+              p95,
+              total: rxTotal + txTotal
+          }
+      };
   }
 
   const expr = metricMap[metric];