I'm making this topic as a sort of clearinghouse for slowdown/graphical glitches, to be updated as needed. This includes characters 'moonwalking,' pointer trails, and slowdown (particularly with spells).

-The first easy to solve glitch is when characters seem to be running backwards (or doing the moonwalk). Going to video options and turning on software mirroring seems to do the trick.

-The game can suffer pretty bad slowdown when walking through the hive, and the wonderful spell animations seems to freeze it completely. It seems that Vista and Nvidia cards are to blame here. For any remotely modern computer, you shouldn't be having any slowdown. The culprit here is direct draw and hardware acceleration. Turning hardware acceleration completely off is impossible under Vista (normally). There are plenty of solutions to this, but I've only found one to work to completely eliminate slowdown:
-You'll need to download the DirectX SDK. It's about 400 MB in size (you can google it or find a link in the thread I'll mention). Once installed, go to Directx Control Panel>Direct Draw. There, uncheck the box that says 'Use Hardware Acceleration. This is discussed in this thread, which contains a link to the download:
http://blog.yimingliu.com/2008/04/16/baldurs-gate-1-graphics-glitch-and-disabling-nvidia-hardware-acceleration/
-I'll link to this thread from the Spellhold Studios forum (which is an excellent source of Planescape info/troubleshooting). The first post from Bigg contains a summary of all the possible solutions discussed later in the thread. Unfortunately, none of them worked. Only the 'D3D Windower' stopped slowdown, but I could never get the bar at the top to go away, nor did the options work to allow me the mouse to move the screen. Here's the thread: http://www.shsforums.net/topic/30840-ie-games-and-nvidia-series-8-video-cards/

-Pointer trails seem to pop in the menu screens and in the dialogue box, but fortunately not in the game. From the link above, just install the 'nvidia fix.zip' from the first link. It seems to help, but this issue I haven't been able to find a perfect fix for.

I'd encourage anyone else to post their own solutions as well. For information purposes, I'm using the excellent widescreen and UI mods (someone on GoG should have created another thread about them) and running this on Vista with a Nvidia 8600M GT.

Excellent. Thanks a bunch!

Thanks for info. Apart from crashing on exit (due to ntdll.dll incompatibility) I had one more problem with my installation - moonwalking.
And software mirroring fixed it - thanks a bunch!

I've also only encountered pointer trails when hardware acceleration is turned off/

I was able to get the D3DWindower to work at 1280x720, it won't go full screen. It fixes the slowdown issues for me. none of the other fixes worked.

Even with the nvidia fix I'm getting some nasty pointer trails (8600M GT, Win7 x64). Anyone know of a solution?

I've installed the nvida fix and that helped a lot, but the framerate drops a lot whenever I highlight a door/chest. It's not a big deal since I can quickly mouse away but somewhat annoying. I'm using Vista with a geforce 9600m for note.....

I had some performance issues too with my system.
Win7 32-bit
Intel Core i3-530 (4x 2.93 GHz)
4GB RAM
GeForce GTS250 (using 2 monitors)

Spell animations were extremely slow. Compatibility mode for Win XP SP 3 and disabeling Visual themes and Desktop compositions helps me a lot. (Options translated from Dutch version so they might be called a little different)

Have you turned hardware acceleration off? I've found that with it on at all the game lags.

With the CD version, you used to need to turn off 'Triple Buffering' for the game to get things to work well in XP. You can do this in the nVidia control panel (3D setting -> Manage 3D settings -> Program settings. 1. Browse for torment.exe. 2. Scroll to the bottom of the settings list).

Just tried it on the GOG version, and all is well. No spell slowdown/glitches, no crashes so far. Oh, I also have it set to XP SP3 compatibility, but was still suffering from the spell issues. Might try with compatibility off and see if it still works well.

Should be an easy fix for nVidia users. Not sure if there is an equivalent option for ATI/AMD cards, though.

EDIT: Never mind. It seems I just got lucky for a bit. Still having the same issues.

I had this problem, the pointer trails within the menu and character creation screens. That was ok, I could deal with that. However, I had a flickering on the pointer within the game, as well as Mort and a few other characters. Researching further, I ran across the GoG common troubleshooting steps http://www.gog.com/en/support/planescape_torment/_i_b_read_first_b_common_troubleshooting_steps_i_ and noticed the following line: This worked for me beautifully. Granted, I'm not running under Crossfire now, but the game works great and it's easy enough to switch back if needed.

i am running it under vmware workstation on a windows xp sp3 guest and get flashing cursor with hardware acceleration on and mouse trails (in all but main game screens).

reading the text file that accompanies the game, the mouse trail is a known issue and is supposed to be fixed by turning on the software rendering in the game, but i have tried that and still get trails (although now some of them disappear after a few seconds showing that the change did have some effect).

the flashing cursor issue is a known issue with the vmware display driver (known as far back as at least 2008 according the message on their forum) and the only guidance is the switching off of hardware acceleration - which did work but as mentioned introduced the trail glitch.

am going to try installing on a host to see if i can remove both issues, but as of now it seems running it in a vm is going to have problems.

So exactly how much testing goes into a game before GoG releases it on their site? It would be nice if there was a "known issues" FAQ for each game so that buyers could make an informed purchasing decision.

Does anyone else get a strange thing where the characters seem to bounce around a tiny bit after installing the nvidiafix? It solved my slow down problems, but it brought up that weird new one.