I had the same thing happen to me.  I did manage to finish the game (thanks to my godlike unclean beast) but is got very annoying very quickly.

Yeah, I couldn't figure out the cause but I remember seeing creeps stuck and tails wagging after the game had slowed WAY down. The first time it happened I thought it might have had something to do with my graphics, but i turned everything from high to low, and it made no difference at all. but it was definitely taking 2-4 seconds real time for every 1 second game time.

I´ve got this negative simspeed on the waterfall map, too. But only in Beta 1A, the first build runs very well versus AI.

Ive only seen monsters get stuck on that map once and it happened 3 times in the 40 minutes i played and all 3 times it was the giant but he only got stuck at the middle where the monsters usually fight so it was easy to take care of  other then that all of the other monsters went smooth.

oh wait the flying dudes would fly directly from the portal across ur spawn point over the gap and into the battle but yea no slowdowns and other then those 3 giants nothing else got stuck for me in the map

Definitely saw this on the Mine map with a Torchbearer today.

On the up-side, it made me definitely want a way to do such a thing deliberately from the game configuration setup, because with ultra-high frame rats and relatively low sim speed, I could really get in and enjoy the artistry and beauty of the art in the game. The animations, even on the mass of zergs, are absolutely fascinating to watch.

Next release, I'd love to have game speed and portal output rate settable ... and I'll drop the first and jack the latter just for that "wading through masses in slow-motion majesty" feeling.

those catapult guys just ignore u and so do most other monsters its kinda annoying

Path finding has serious trouble in the Mine map, if I click next to the flag from my start position the demigod walks to the 'north' i've to click somewhere nearer to get him walking in the right direction.

I would create a new post for that. They want one bug per thread.

A LOT of people are getting this problem... Really anoyying!!

It was the catapultasauruses for me.  My side's got stacked up behind the slanted tower/wall combo, until it got so bad that I couldn't even count the tails anymore (there were a lot and they were spinning in circles).  Eventually something happened and they all recovered and started moving again and the game picked right up.  Unfortunately, before long they started stacking again and the game began to lose speed once more.

I have had this problem also.  I will not bother describing it again but this is obviously a very common issue.  I did not realize it was only on the new map since i have not played the falls since the last release

Going to add a "same here" to this. Once the big units start to spawn (Giants, mainly), there are HUGE bottlenecks. Dozens and dozens of units (no hyperbole) spawn and get stuck along corners, buildings, and walls, usually around the same area. For the mines map, that means the first corner after the base (the sharp turn with the defensive structures). Once the units start to build up, memory usage spikes and the game slowly descends into a crawl.

I only played once on that map (yesterday evening), and it also happened to me.

On the other (3 v 3) map, I had never experienced any significant slowdown.

Yesterday evening, on the 2 v 2 map, suddenly, with no apparent reason, the game dropped to a crawl -- even though I had the same general settings than on the other map.

I was a level 16 demigod, then.

Slowdown on 2v2Mine due to pathing failures is known. Pathing is being redone.