It's certainly possible, but another thing you can often do is just not depend on slow computations during interactive development. This is how I usually work on code in Python: with https://github.com/darius/halp I have repl-like examples in my source code, and Emacs reruns them all at a keystroke and tells you if any output changed; mostly it's no trouble to keep helpful examples that can all be rerun in a small fraction of a second.

IPython is fancier and can be used with expensive computations, so this might be a dead end, but I didn't want to have to think about whether the state of the examples was ever out of sync with a fresh reexecution of the code (and also I wrote this a long time ago). I thought I might get to cleverer incremental update methods eventually, but it hasn't been worth the trouble to try when the above workflow has worked well enough.