This is a work-in-progress note pad of all the things I've found about gcc to make the best code possible.
Ever.
Generally, most other PC libraries are okay, including SDL and OpenGL, but ixemul will take awesome performing code and make it run like it's walking through a tar pit -- especially on any stdio file operations. When porting "small and dirty" POSIX applications where performance does not matter, then who cares, use ixemul. For everything else, don't. Don't even use libnix. Try as much as possible to use AmigaOS native functions like AllocVec over C standard functions like malloc.