How many layers are in the comp?
How many of them have effects applied?
How big are the biggest layers? 2000×2000?
The remaining render time is based on the current frame rendering. If it’s an easy frame, AE will think the render will be done soon. So, if the frames after the first estimate were more complex than those rendering at the time of the first estimate, the first estimate will be revised upwards to account for that.
Try twirling down the “render details” triangle (in the queue) when rendering. See what your bottleneck is. Some effects are render hogs.
Steve