FWadCollection::GetLumpsInFolder performance problems

[UsernameAK]

FWadCollection::GetLumpsInFolder makes lag because it basically bruteforces all lumps in all wads. It affects performance of wads that use ACS SetFont heavily and have large amount of lumps.
The well-known wad that is affected by this bug is LSD. Inventory in this mod is made with ACS, and it lags heavily (drops to 1-2 fps) when it's open. Profiling showed that the performance bottleneck is exactly FWadCollection::GetLumpsInFolder.

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LSD can be downloaded from here: https://drive.google.com/drive/folders/ ... jSUdKNOwSq
GZDoom compatibility patch for it is attached

https://github.com/coelckers/gzdoom/blo ... .cpp#L1344 - the part of code which makes lag

[Graf Zahl]

What crazy stuff does this mod do to trigger such an edge case?

[_mental_]

It calls ACS SetFont with non-existing font named NORMAL. GZDoom tries to create it every tick.

[Rachael]

Maybe GZDoom should cache the error state of font creations so that it does not continue attempting this?

[UsernameAK]

The texture really exists. It's in gzdoom.pk3's graphics folder. That weird trick is used to use mouse in older ports.

[Graf Zahl]

This looks more like an error in the font checking code, it shouldn't try to recreate a font if something with the name is found.

[_mental_]

The texture really exists. It's in gzdoom.pk3's graphics folder.

Where is this texture exactly? Also, querying FWADCollection and FTextureManager for it returns nothing.

[UsernameAK]

The texture really exists. It's in gzdoom.pk3's graphics folder.

Where is this texture exactly? Also, querying FWADCollection and FTextureManager for it returns nothing.

Oh, i was wrong. It really doesn't exist. If you put some stub texture, it stops lagging.

[_mental_]

The simplest solution seems to be a removal of this condition. So, empty font will be created regardless of texture existence, and lumps lookup will happen only once.

[Graf Zahl]

V_GetFont must not create placeholders, it would break the entire font system. This is simply bad use. The CheckFont ACS function exists for good reasons.