Here are infos on how to tune Linux for better performance on the following hardware. It should apply to other machines than the specific Toshiba modell provided that some of your HW is the same.
It is meant as a supplement to Enrico Segre's page and jxh's page that describe general configuration more in detail.
Toshiba maintains quite good Linux pages. Useful tools are Jonathan Buzzard's Toshiba Utilities, klaptop and apm.

I'd be happy to hear from you if you've succeeded in resolving any of the remaining problems on your toshiba.

Enjoy - Tomas Pospisek

Laptop	Toshiba Satellite 1800-712
Multimedia audio controller:	ALi Corporation M5451 PCI AC-Link Controller Audio Device (rev 01)
IDE Interface	ALi Corporation M5229 IDE (rev c3)
VGA compatible controller	Trident Microsystems CyberBlade XPAi1 (rev 82)
-	-
Kernel	2.4.22
XFree86	4.3.0

The performance under a standard distribution kernel was painfully slow - hickups in the X screensaver were the rule. Freezes for a few seconds up to half a minute after heavy disk access happened. The ALi 15x3 driver remedies that - it quadrupled disk performance (!). Make sure that you put all settings in the BIOS to maximum performance (even the Fan setting!?!?!?!!!) otherwise the driver won't be able to switch on DMA. Tuning the IDE system with hdparm didn't bring any advantage. The IDE subsystem is currently performing at:

petertosh:~# hdparm -Tt /dev/hda

/dev/hda:
Timing buffer-cache reads:   128 MB in  1.20 seconds =106.67 MB/sec
Timing buffered disk reads:  64 MB in  3.48 seconds = 18.39 MB/sec

See also my results here. I used the rawtest program to test raw read/write throughputs. Under the 2.4.18 kernel the sound module would die after a suspend/resume if it had some client playing music. The 2.4.22 kernel fixes that problem. At the moment I've compiled the VESA Framebuffer driver into the kernel. The Trident FB driver is giving me rather interesting psychadelic effects. For X I'm using Alan H's trident X driver, version 4.3.0.

I needed to upgrade libxine from 1-beta9-1 to 1-rc0a-1 to be able to watch movies - before that X would crash with the x11 driver and performance with the xv and the xshm driver would be horrible. I've read somewhere that not using ACPI would fix the problem that the laptop will freeze after a reboot. It didn't fix it here - it's still freezing.