First off, just want to say thanks for Factorissimo and Factorissimo 2. I'm a huge fan and absolutely love the work you do.

My friends and I haven't been able to finish a game using Factorissimo 2 due to performance issues. When looking at the time used by the game Factorissimo uses almost all of the script update. I'm assuming it's because of the destroying/creating of items on belts/liquid.

Do you plan to optimize this in any way?

Again, thank you for hours of enjoyment.

Factorissimo2 is already optimized, you just didn't use the connections properly. Here's how to fix your save in few easy steps:

Are you using many belt connections? If so, use chest connections with loaders or robots instead, they're just so much better for performance than belt connections. Also don't use faster belts than necessary.

Are you using many fluid connections? If so, set the connections to transfer mode instead of balance mode, use bulk transfer pipes instead of regular pipes, and lower the update rate as far as it can go (to once every 120 ticks) instead of irresponsibly using regular pipes in balance mode and setting them to update once every tick or something.

Are you using combinator connections? Just don't. Avoid them whenever you can. And if you can't avoid them, decrease the update rate as much as possible, and don't send more signal types than you need. They're just horribly bad for performance and there's no way I can make them any better.

tl;dr: You didn't read the guide and it's your own fault you have bad performance.