> For the complete documentation index, see [llms.txt](https://docs.cb21829.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.cb21829.org/ftc-java-advanced-guide/loop-times-and-optimization.md).

# Loop times and optimization

Fast loops make controls feel tighter and more accurate.

### Why hardware calls matter

Every sensor read or motor write sends a command to the hub. These calls block and cost time.

The fix is simple:

* make fewer calls
* reuse values within the same loop
* use bulk reads

### Rule 1: never read the same hardware twice per loop

```java
int liftPos = lift.getCurrentPosition();
if (liftPos > 100) { ... }
telemetry.addData("pos", liftPos);
double p = pid.calculate(target, liftPos);
```

Read once. Reuse everywhere.

### Rule 2: use bulk reads

```java
import com.qualcomm.hardware.lynx.LynxModule;
import java.util.List;

List<LynxModule> allHubs = hardwareMap.getAll(LynxModule.class);
for (LynxModule hub : allHubs) {
    hub.setBulkCachingMode(LynxModule.BulkCachingMode.AUTO);
}
```

Bulk read modes:

* `OFF` — every call hits hardware
* `AUTO` — recommended default
* `MANUAL` — slightly faster, but easier to misuse

Manual mode looks like this:

```java
for (LynxModule hub : allHubs) hub.setBulkCachingMode(LynxModule.BulkCachingMode.MANUAL);

while (opModeIsActive()) {
    for (LynxModule hub : allHubs) hub.clearBulkCache();
}
```

### Measure your loop time

```java
ElapsedTime loopTimer = new ElapsedTime();
while (opModeIsActive()) {
    double loopMs = loopTimer.milliseconds();
    loopTimer.reset();
    telemetry.addData("loop (ms)", loopMs);
    telemetry.addData("hz", 1000.0 / loopMs);
    telemetry.update();
}
```

FTC Dashboard is the best tool for live tuning, plotting, and path visualization.

### Other wins

* avoid multithreaded hardware calls
* keep telemetry lean when chasing performance
* skip repeated motor writes if values did not change


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