Performance Enhancements Resources
Jython benchmarks (from PyPy's suite): http://freya.cs.uiuc.edu/~njriley/benchmark.html
Benchmark plots (currently broken): http://freya.cs.uiuc.edu/~njriley/plots.html
Ideas
jbaker & thobe's JavaOne '08 talk: Jython Implementing Dynamic Language Features For The Java Ecosystem
GC Expense
Our algorithms are not always the problem, sometimes it's memory {de}allocations that slow you down
dict allocation
PyStringMap/PyDictionary pay a penalty on allocation now that they're backed by ConcurrentHashMap. We could probably tweak the ConcurrentHashMap initialCapacity, concurrentLevel to reduce this cost
Frame creation
Frames are allocated for every Python method call, which is a GC expense. CPython (and JRuby?) recycle frame objects. Reducing the number of fields on the frame can also help (but this likely isn't possible)