I found, that even if Chest is closed, MC still renders its Ender Portal

This caused slightly FPS lag. It can be seen on Spark profiler

Please skip drawing portal if chest not opened 😀
Or add config option to disable this "space" render at all.

Please provide issue template, so issue makers will know what information is appreciated.

'Causing slignt fps lag' is very much an overstatement.

However, the Ender Chest has done this since 1.15.x: https://github.com/TheCBProject/EnderStorage/blob/1.15.x/src/main/java/codechicken/enderstorage/client/render/tile/RenderTileEnderChest.java#L55

In the future, please provide more in-depth information about which mod version and Minecraft version you are reporting the issue for.