Summary:
Can I program a \"thick client\" game in C without reinventing wheels, or should I just bite the bullet and use some libr
I believe you are working under a fallacy.
There are several frameworks out there specifically for game programming --- written by people with much experience with the complication of game design, almost certainly more tha you do.
In other words, you have a "High risk of performance issues" if you DON'T use a framework.