All USB-Loaders use the IOP (Co-Processor) to move data from USB to RAM.
This causes (alot) CPU-Cycles/Ticks to be used, only to move data around (no DMA).
PS2ESDL does some stuff, which isn't data-transfer-related on EE (Main-Processor in PS2-Mode), instead of how most loaders do it,... on the IOP.
Now if enough IOP-RAM is free, the sector-caching-feature might have some influence on atleast a few games.
OPL is a 'pussy' too, when it comes to fragentation on USB.
Argh,... SP193 was faster.
Additionally to what he said:
The InGame-Driver is also smaller, when it doesn't need support for filesystems.
The InGame-CDVD-Replacement-Driver must be as small as possible, or atleast not bigger than the one of the game which is about to be started...
Well,... Maybe not in all cases.
There might be enough games, which are still compatible.
PS2 V7/DMS3 V2 (FW:2.4b7); Seagate Baracuda 200GB
PS2 V7/CC1.0 (FW:34 hacked v2 BM:2.1.6); Maxtor DiamondMAX9 PLUS 160GB
PS2 SCPH-30004R; NoMod+NoLaser
3xSony MC 8MB
MAX/Datel 16MB with Boot-CD
Custom FMCB 1.8b+ Beta-Build, my AIO 0.5, Sony&xRhino-Linux