You can never prevent the GC cycle in CPython at the end of a block (context). You can only prevent the GC that tries to break reference cycles. If your class does crazy things at destruction, like "time.sleep(10)", and you create an instance of the class inside a function, when that function returns you will pause CPython even if you call gc.disable()

You also cannot disable the minor collections in PyPy, only the major collections, but once the JIT kicks in PyPy can prevent some of the object churn by optimizing instances away.

Yeah. Avoiding slow things like classes, threads and adding time.sleep(10) is the trick.