I definitely do think you can improve processing speed with time and practice. The brain is so plastic that it is difficult to imagine that you can't.
My son at age 6 had a roughly 45 point spread between his PSI and other scores. We have done piano, competitive swimming, and lots of flashcards. He has written into his IEP (which is for hearing loss) that he can have extended time on tests, but he has never used it.
Flash forward 3 years- is he the fastest kid? No. It still lags other things. BUT- with alot of work and practice, he can complete timed tests appropriately (OLSAT, STAR test, SCAT for CTY). I do think he will have trouble competing at high level math competitions if speed is an important factor.
so... practice, practice, practice.
