Some little tests on my Amiga1200 with 1230/50 accelerator:
Netsurf took - with best configuration - 35,6 seconds to load amiga-news.de using the version before, now takes 31,8 seconds. Jumping to aminet.net (35 seconds) and back to amiga-news.de (31,1 seconds). Holding shift and reload it, Netsurf took 30,8 seconds. So I guess if I reload it ten times I can break the 20 seconds mark...
If you keep it at, at some point you'll be able to see web pages before you have decided to visit them, which leads to the possibility of being able to read next week's lottery numbers

But seriously, the longer you use the web browser, the better the new memory management system will adapt. When you switch to a new web page, NetSurf has to break up the memory allocated for all the old page's components, then reuse it for the new page.
Imagine smashing up all your crockery after dinner, then glueing it all back together for the next meal. The fragments will become smaller and smaller over time, making it harder to find those which fit together well enough. Larger fragments need to be broken up into smaller pieces to make them fit with the rest.
That's exactly the problem which NetSurf has. The new memory management system helps here by sorting the fragments into bins from which they can be retrieved more easily without having to smash larger fragments. The longer you use it, the better the new memory management system will know which bin sizes are needed the most, and the more readily-available fragments it will keep at hand.