First of all, here is the basics of my computer while running KSD Aces:
Intel Core2 Quad Q8300 @2.5GHz
Intel DP434BF LGA775 Mobo
8gig of dual channel DDR3 1333 RAM
2x 2TB WD Black HD
nVidia GeForce GTX 560Ti 1024MB GDDR5
Nothing fancy, and did not stretch the pocketbook even when built years ago. Plenty strong enough to run SH4. I encountered a similar sized convoy in the Western Approaches just a bit ago. I was doing 512x TC when a hydrophone contact was reported, dropping me to 1x TC. Followed it for a few minutes to determine approximate direction and went for an intercept. We initially had contact with a DE on the southern flank, which was difficult to track at first, but we did manage to finally get around the group before daylight and submerged in front of them.
We went to went to 100m and 256x TC for the group's approach. As they came closer, we did see a "stutter" in the TC, which dropped us to 1x several times, and as we tried to get back up to 256x, got quite a bit of lag, but nothing any worse than what we see when coming back into home port, and have to run at 64x TC. As we eventually made sound contact with most of the group, the lag would get worse as each ship would spawn.
We were slightly off-center from the convoy's track, but made visual contact with the southernmost leading DD, and then the middle leading DD. We were deep by this time, Ahead 1/3 speed and silent, managing to get inside the screen to attack, coming up to PD. While doing so, the rest of the group were in contact, so we had sound lines 360 around us. Naturally, it was a bit too dark to get good targeting, so we shot the rear tube at a closing DD / DE (never identified) and a spread for the 4 bow tubes toward the dark shapes in front. We called for 110m and Ahead Flank, and as we were passing about 50m, we heard the first of several explosions. Once getting deeper, we went back to silent and turned to parallel the group and eventually reload the tubes. Saved the game and am now doing this.
We'll see if we get a good game re-load a bit later, and try to determine the damage we caused... The game definitely "telegraphs" a group is getting close with the stutter at even a medium TC level, and the larger the group, the more noticeable the stutter, sometimes getting to be a very definite lag. But I have not had a CTD yet, though I have not been in contact with a "large" group. The one I am under now is probably a couple of dozen of merchants (maybe less) with the escorts, so maybe 30-32 ships altogether, at the most.