My phone: Xiaomi Redmi 4X
I'm experiencing A LOT of lag spikes too I had around 40 - 60 fps, I'm using resource pack (Bedrock tweaks - never had any lag problems with it) and I'm also using a shader (which removes the selection circle - never had any problems with it too) and after this update I'm still using the same resource packs and have around 15 - 35 FPS, it takes long for game to respond like clicking a button and opening a door with it, or the sounds are delayed too or opening inventory takes like around 1 - 3 seconds. I hope this issue gets resolved quickly.
Edit: I deactivated all my resource packs put the video settings to lowest as possible and it still lagged (I had around 25 fps) I also discovered that if I load new chunks really quickly, they don't actually load and even the already-generated terrain is on some blocks unloading and loading quickly (like flickering between it).
Edit 2: Inventory is really laggy too, it takes too much time to move item from one slot to another slot and sometimes (after you open inventory and its lagging) there's a glitch that when you click for example the open inventory button, you need to click little below it and basically what that is, is that Minecraft thinks you are clicking higher, than you are actually clicking (and this bug was in lower versions too).
Edit 3: I also think that this is a rendering issue because it takes long to play the sounds and probably the game plays the sound when what did you do, is rendered, same thing with opening world and loading chunks... etc.
I've just experienced this issue, can someone provide instructions for updating LWJGL to 3.x unofficially?
More specifically, what file from https://www.lwjgl.org/download replaces lwjgl_util?
Maybe your world got corrupted but I'm not entirely sure.