At the end of my animation, the animation pauses a bit then loops again, how can I stop the slow pause, and let the loop work fluently?
One common mistake with looping animation is to have the first and last frames share the same values. You want the frame after the last to be the same as the first.
Another cause for pauses in looping animation is to have bezier curves to ease in and out of the first/last frames. Using linear interpolation gives you a constant speed that matches the surrounding frames. Select the keys in the graph editor or dope sheet and press T to change the type.
Two cubes with the same rotation values keyed on the same frames, the red one uses linear interpolation while the blue one uses bezier.
You could either edit your action in the Dope Sheet / Action Editor:
Say you want to have a 100 frames long animation but the last keyframe is located at frame 75
Then you would have a noticeable pause.
You could select the last keyframes RMB and move it to G frame 100.
Or if you don't want to stretch the animations duration you should set the actual end frame (in my example 75) in the Actuator