it all depends on how big or complex your 'object ' actually is!
TC will use up to a max. of 2GB of memory under 32-bit XP, whether you have 3GB or 4GB. However, v21.1 is generally less prone to crashing than previous models, IMHO, so you might need to leave it alone for a while longer, or, look at simplifying your drawing file, or, upgrading your PC!
I am still using XP with 4GB memory and, for the most part, TurboCAD works just fine, even rendering large complex drawings. I would advise using GDI only.
I hope this helps.