It seems to be a problem of lag, but usually when i get lag it dosent crash, what in the mod could be making it crash? Or is it forge
We can't tell you whether that's Forge, you have to try yourself. Simply uninstall the ReplayMod and check whether it still happens. If it doesn't it's probably got to do with the ReplayMod, if it does it's probably Forge.
You may also try to uninstall Optifine (never heard of anyone having these kind of issues with Optifine and I think this one is rather unlikely).
What is most noticeable is that you're using an outdated version of Forge. Updating it to the latest recommanded version might help.