What you'll need:
-A hacked Samsung i8910 or other S60v5 phone (refer to THIS post)
-The Symbian^2 filebrowser from Hyperx from HERE (download and install to your phone)
Open the filebrowser that you just installed. It'll be at the bottom of your menu. Once you've opened it, click on 'Options', 'Tools', 'Avkon cache' and then select 'clear and disable'.
After you've disabled it, again go to 'Options', 'Tools', 'Avkon cache' but this time select 'Enable'.
Close the filebrowser and open your 'applications' folder. It'll still take a while to load, but this is because the cache has to be rebuilt. Exit from it and open it again -- you should notice an increase in loading speed.
I hope this works for you. It certainly worked for me. I'm not sure if it will work on Sony Ericsson or Nokia s60v5 devices, as I don't have any, so please leave a comment if you try with yours.
Credits to Hyperx for the procedure and extracting the filebrowser - thanks!