Prefer performance.now() over Date.now()

performance.now() is faster than Date.now() as there's no need to
consult the system clock. The more important part of this is that
performance.now() is monotonic and is guaranteed to never to backwards.

src/common/input/WriteBuffer.ts

@@ -137,7 +137,7 @@ export class WriteBuffer extends Disposable {
    * effectively lowering the redrawing needs, schematically:
    *
    *   macroTask _innerWrite:
-   *     if (Date.now() - (lastTime | 0) < WRITE_TIMEOUT_MS):
+   *     if (performance.now() - (lastTime | 0) < WRITE_TIMEOUT_MS):
    *        schedule microTask _innerWrite(lastTime)
    *     else:
    *        schedule macroTask _innerWrite(0)
@@ -158,7 +158,7 @@ export class WriteBuffer extends Disposable {
    * Note, for pure sync code `lastTime` and `promiseResult` have no meaning.
    */
   protected _innerWrite(lastTime: number = 0, promiseResult: boolean = true): void {
-    const startTime = lastTime || Date.now();
+    const startTime = lastTime || performance.now();
     while (this._writeBuffer.length > this._bufferOffset) {
       const data = this._writeBuffer[this._bufferOffset];
       const result = this._action(data, promiseResult);
@@ -186,7 +186,7 @@ export class WriteBuffer extends Disposable {
          * responsibility to slice hard work), but we can at least schedule a screen update as we
          * gain control.
          */
-        const continuation: (r: boolean) => void = (r: boolean) => Date.now() - startTime >= WRITE_TIMEOUT_MS
+        const continuation: (r: boolean) => void = (r: boolean) => performance.now() - startTime >= WRITE_TIMEOUT_MS
           ? setTimeout(() => this._innerWrite(0, r))
           : this._innerWrite(startTime, r);
 
@@ -202,7 +202,7 @@ export class WriteBuffer extends Disposable {
          * throughput by eval'ing `startTime` upfront pulling at least one more chunk into the
          * current microtask queue (executed before setTimeout).
          */
-        // const continuation: (r: boolean) => void = Date.now() - startTime >= WRITE_TIMEOUT_MS
+        // const continuation: (r: boolean) => void = performance.now() - startTime >= WRITE_TIMEOUT_MS
         //   ? r => setTimeout(() => this._innerWrite(0, r))
         //   : r => this._innerWrite(startTime, r);
 
@@ -222,7 +222,7 @@ export class WriteBuffer extends Disposable {
       this._bufferOffset++;
       this._pendingData -= data.length;
 
-      if (Date.now() - startTime >= WRITE_TIMEOUT_MS) {
+      if (performance.now() - startTime >= WRITE_TIMEOUT_MS) {
         break;
       }
     }