Hello Mkobzar.
This slow at beggining, fast in middle and slow at end is because of default ease-in and ease-out interpolation in 3ds max.
You need to look at the interpolation curves and adjust them.
Hearing this it sounds like you are are fairly new to 3ds max and animation (Correct me if I'm wrong). Please follow a lot of 3ds max tutorials or consider applying for a course.. Lynda.com is also a good place to learn about 3ds max.
Nevertheless watch this video about the curve editor:
https://www.youtube.com/watch?v=IOrDPidE8uU
To make the lines thin make them as tick as 0.01 rendered and then turn the noise filter all the way down
Very little people even in beyond 3D seem to adjust the curves or spend time on them at all.. even big professional companies which is a big shame as it's amateuristic. Hope this helps and good luck!