How to fix Apple Pencil lag and palm rejection problems

The short answer

Lag and palm marks are two different faults with two different fixes. Lag is about how quickly and how densely the app turns your movement into a line. Palm marks are about which touches the app decides to accept. If one guide tells you to "restart the iPad" for both, it is guessing.

Palm rejection first, because it is easier

Turn on a pencil-only mode

The reliable fix is not clever palm detection — it is telling the app to accept nothing but the pencil. Flying Chalk has a switch for exactly this, and once it is on you can rest your whole hand on the glass and it leaves nothing behind. The trade-off is deliberate: with pencil-only on, a fingertip cannot draw either.

Why palm rejection sometimes fails anyway

The usual cause is an app that only ever looks at the first touch it is given. Your palm lands before the tip does, the app locks onto the palm, and the pencil never gets a turn — so the "pencil only" setting does nothing while a stray mark appears anyway. A correctly built canvas accepts multiple simultaneous touches, scans them for the one it is willing to draw with, and then locks onto that one for the rest of the stroke. If your app misbehaves here, no iPad setting will save you; it is the app.

Things that genuinely help outside the app

Keep the glass clean and dry, since a damp screen produces phantom touches; take off a screen protector that is lifting at a corner; and check that a third-party stylus is actually recognised as a pencil by the system rather than as an ordinary finger, because a stylus that registers as a finger can never be filtered out.

Now the lag

Distinguish real latency from a broken-looking line

Two very different complaints get called "lag". One is that the line trails behind the tip. The other is that fast strokes come out as visible straight segments with corners in them. The second one is not latency at all — it is undersampling.

Why fast strokes go polygonal

On a high-refresh display the system can collect several pencil samples inside a single frame, and it hands them over as a batch alongside the latest one. An app that only reads the newest position and throws the batch away is quietly discarding most of what you drew, and a quick flick collapses into three or four straight edges. Flying Chalk reads the whole batch, which is the reason its canvas is built directly on the low-level view rather than on a convenience gesture API that never exposes those extra samples. If a different app shows you polygonal fast strokes, that is what it is doing wrong, and there is no setting you can change to fix it from the outside.

What you can change

Close whatever else is running, especially anything recording or mirroring the screen — screen sharing and capture add work to every frame and it shows up as sluggishness in exactly the app you are drawing in. Give a very large canvas or a deep stack of layers a chance: any app that redraws a long history for every frame will slow down as the drawing grows. And if the whole system feels slow rather than just the pen, treat it as a device problem, not a stylus one.

Check the pencil itself

A loose or badly worn tip is a real cause of skipping and dropped strokes; tips screw on and are replaceable. A pencil that is nearly flat can behave erratically before it dies outright. And a pencil that has drifted out of pairing will often work partially, which is far more confusing than not working at all — re-pairing it costs a minute and rules the whole question out.

A test that separates app from hardware in thirty seconds

Draw the same quick zigzag in two different drawing apps. If only one of them produces corners, straggling lines or stray palm marks, the hardware is fine and you have found an app limitation. If both do it, look at the tip, the pairing and the battery before you look at anything else.

Related guides

• Which Apple Pencil works with my iPad? How to check properly
• Drawing on an iPad with your finger vs an Apple Pencil
• Apple Pencil pressure vs tilt vs azimuth, explained