After installing a Mod My FPS has been below 10 FPS

Hello,

A few weeks ago I downloaded the mod,Pixelmon,and once this mod had downloaded,I loaded Minecraft. But when I got onto Minecraft the home page and all my worlds had a frame rate of 1-10 FPS.

At first I thought it was a glitch and left my Minecarft alone for a month.But when came back it was still like this.So, I did a little digging and found some Solutions.I tried these,but none of them worked(Updating graphics card,using Microsoft safety app Etc)

I have tried everything I can possibly think of and got a I.T specialist who could not figure out what was wrong.

I would appreciate help.

Thanks,
Tuxedobear626