Hey guys, I wanna get into speedrunning 1.7.2 minecraft any% glitchless, and I was wondering if I was allowed to use optifine ? My pc is not a gaming tool at all but with optifine the fps are kind of stable. Is it allowed in runs ? Thanks in advance

It is allowed. Just make sure that you remember to check off that you are using it when you submit the run.

with some restrictions, but yeah

Yes, just read the optifine rules and follow those please

What exactly are the restrictions?
Or where can I find the Optifine Rules?

Go to the leaderboard -> View Rules -> Game Rules -> Scroll down until you see: "RESOURCE PACKS/MOD RULES"
Here you can find all Optifine rules and option to change.. anyway if you can't find them look below:

No Mods are allowed except Optifine. Additionally, the following settings must be set:
No Zoom
No Fast Math
No Clear Water
No Dynamic Lighting
No Lazy Chunk Loading
No Render Distance higher than the version you're playing on normally allows.
No shaderpacks can be used in the run.
Badlion client is considered a mod and is banned.