> Those debuggers are ultimate "trace loggers", logging each statement and variable -- and thus they have inevitable overhead. rr only logs sources of non-dete

> Those debuggers are ultimate "trace loggers", logging each statement and variable -- and thus they have inevitable overhead. rr only logs sources of non-determinism, such as system calls (which includes I/O). Then all the deterministic state of the program is reconstructed at runtime using the recorded non-determinism. So having lots of state doesn't necessarily affect trace size but you're right that lots of I/O will.