Pauses like that are normally attributable to resource starvation in the computer. That can be memory, video card, and/or sound card related.
In most systems, it is probably system memory related. Cutting down the "Maximum Texture Size" in the game's "Video Settings" is the quickest way to determine if it is resource related.
Also note, you cannot go by the reported video memory usage in the in game. It is not accurate due to how bideo card manufacturers decided to report memory used. If you have anti-aliasing enabled in your video card, those large textures can take a long time to process by the card.
On NVidia video cards, the 9x.xx drivers can also cause massive stuttering as well.
Onboard sound chips use more CPU cycles than a good PCI card would. So if your CPU is at the edge of having too much to do, these chips will push it right on over the edge. Adjustng the hardware sound acceleration down a notch from Full will help reduce the CPU load.
Lastly, the number of and type of background processes is a contributing factor to poor performance. Open the Windows Task Manage, select the "Processes" tab. In the lower left cornder is the total number. It should be around 19 to 21 for a reasonably clean Windows XP/2000 system.
Right next to the total count is the CPU usage percentage. It should be bouncing like a heartbeat between 0 and 1 (maybe 2 on occasion) percent. If there is any deviation to this, then something is amiss. You can also start the game, minimize it, then check the game's CPU usage. It should be at 99 to 100%. Anything less, then something is amiss.
If the processes look good and the CPU usage is fine, then you are probably pushing the video card too hard. Simply reduce the "Maximum Texture Size" in the game, disable any anti-aliasing you have forced on, as well as any anisotrpic filtering you have forced. Then go from there.
