# Performance issue with SpotLights.setEnabled and material.maxSimultaneousLights

**URL:** <https://forum.babylonjs.com/t/performance-issue-with-spotlights-setenabled-and-material-maxsimultaneouslights/47473>\
**Category:** Questions\
**Tags:** performance, spotlight\
**Created:** [January 23, 2024, 8:12pm UTC](https://forum.babylonjs.com/t/performance-issue-with-spotlights-setenabled-and-material-maxsimultaneouslights/47473 "2024-01-23T20:12:49Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![ylacaute](https://sea2.discourse-cdn.com/flex024/user_avatar/forum.babylonjs.com/ylacaute/32/31802_2.png) [@ylacaute](https://forum.babylonjs.com/u/ylacaute)\
**Post date:** [January 23, 2024, 8:12pm UTC](https://forum.babylonjs.com/t/performance-issue-with-spotlights-setenabled-and-material-maxsimultaneouslights/47473/1 "2024-01-23T20:12:49Z")

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Hi,

I am experiencing a performance issue with SpotLights when calling the `setEnabled` function. I have an empty scene with a ground and 10 game units (characters). When a unit is selected, I activate a `SpotLight` with a projectionTexture. Each time one or more units are selected, I use the `setEnabled` method on the pre-created SpotLight object (with its texture loaded in advance). Conversely, I use `setEnabled(false)` to deselect.

The problem I’m observing is that the `setEnabled` method takes a significant amount of time, to the point where I sometimes receive the message:  
`[Violation] 'requestAnimationFrame' handler took 496ms`

A workaround that confirms that the issue is related to the `setEnabled` method: if I replace `setEnabled(false)` with `this.spotLight.intensity = 0` and vice versa with intensity 2, it works perfectly and instantly.

The problem seems to be related to this line of code: `terrainMaterial.maxSimultaneousLights = 1000;` With a value of 1000, I encounter the issue, but with 10, there is no lag.

PS: The default value of `maxSimultaneousLights` is 2, which seems surprisingly low. Is there a bug regarding this?

I attempted to reproduce the issue in a playground, and it’s even worse. As soon as I increase the value from 10 to 20, it generates compilation errors in the PG console.

[Playground](https://playground.babylonjs.com/#20OAV9#12980)

PS 2: I disabled shadow and set includedOnlyMeshes to only one mesh (ground) for optimization but it changes nothing.

babylon version : 6.39.0 (+ gltf loaders + debug editor)

Regards

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<div class="post-metadata">

**Author:** ![ylacaute](https://sea2.discourse-cdn.com/flex024/user_avatar/forum.babylonjs.com/ylacaute/32/31802_2.png) [@ylacaute](https://forum.babylonjs.com/u/ylacaute)\
**Post date:** [January 23, 2024, 8:30pm UTC](https://forum.babylonjs.com/t/performance-issue-with-spotlights-setenabled-and-material-maxsimultaneouslights/47473/2 "2024-01-23T20:30:45Z")

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There is more : when using `seEnabled`, I got sometimes some scene flickering and I see FPS going from 60 to 50. If I use the workaround with intensity, no flickering, and the FPS is always at 60.

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<div class="post-metadata">

**Author:** ![Evgeni\_Popov](https://sea2.discourse-cdn.com/flex024/user_avatar/forum.babylonjs.com/evgeni_popov/32/4432_2.png) [@Evgeni\_Popov](https://forum.babylonjs.com/u/Evgeni_Popov)\
**Post date:** [January 24, 2024, 11:11am UTC](https://forum.babylonjs.com/t/performance-issue-with-spotlights-setenabled-and-material-maxsimultaneouslights/47473/3 "2024-01-24T11:11:57Z")

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You can’t have too many lights affecting a mesh, there are GPU resources involved with each light (one uniform buffer per light), and these resources are quite limited. You should search for `maxSimultaneousLights` in the forum. For example

- [Light material limit - #8 by Evgeni\_Popov](https://forum.babylonjs.com/t/light-material-limit/17391/8)
- [Limit to number of spotlights](https://forum.babylonjs.com/t/limit-to-number-of-spotlights/47170)

Note that you can set `engine.disableUniformBuffers = true` to avoid using ubo for lights, and you’ll be able to use more lights simultaneously. However, this will also disable ubo for materials, which may result in a slight drop in performance.

Your PG without ubo support:

> **[Babylon.js Playground](https://playground.babylonjs.com/#20OAV9%2312983)**
>
> Babylon.js playground is a live editor for Babylon.js WebGL 3D scenes

Note that I’ve disabled projection texture, as you run up against another GPU limitation which is the total number of texture units a fragment shader can use. This is around 16 (depending on your GPU), so if you have too many spots, you’ll get an error like `Error: FRAGMENT shader texture image units count exceeds MAX_TEXTURE_IMAGE_UNITS(16)`.