So what we have here with the PS2 is a 1.5x DVD ROM drive which gives an data rate of about 12MB/s (same as the data rate of the USB 1.1 bus).
Also we have a 36mhz CPU which handles the USB host controller (IOP).
The IOP (Playstation 1 CPU which on PS2 mode is used to control all I/O, hence the name IOP or Input Output Processor.) is NOT FAST ENOUGH to process USB at full bandwidth WHILE doing other tasks required by the PS2 OS and GAME.
That's the whole problem here and that's why it will never be solved.
If the speed problem bother you, use the ethernet port instead as it's accelerated with DMA, resulting in less processor power being required. Memory requirements are quite high though (just like with the USB) so getting an PS2 capable of using the internal HDD as data source is totally worth the trouble.
SCPH-10000_GH-001 SCPH-15000_GH-003 SCPH-18000_GH-008 SCPH-30001_GH-005 SCPH-30000_GH-016(V4) SCPH-30001_GH-010(V4)
2xSCPH-10190, 2xSCPH-10350, 2xSCPH-10280
"**** j0 hackers!"
-Sjeep (As seen on TOXIC OS ELF...)