Shouldn't the factory level 1 be able to keep up with the yellow belt modified by bobs settings?
The gray has 15/sec, the yellow has 30/sec, when the yellow pass from inside to outside it get just a little slower, than everything that should be fine starts to clough up.

Are you sure all your belts are yellow, or is there a gray belt somewhere? Try breaking and replacing one of the belts to see if this fixes the issue.

Meh, sorry for that. It isn't the belf or Factorissimo, it's just me not knowing how to math ahhaha. I was combining 2 gray belt at 15/sec with 1 yellow at 30/sec, that should match just fine, but I'm outputting 17/sec on each side and not just 15 itens, so that doesn't add up to 30.

Thanks for the answer, by the way.