I hope I can explain this and that Im using word "interpolation" right...I need a tool that interpolates timing of the notes in non linear way, like slowing down or up. Essentially its the famous bouncing ball effect. Is there a tool that can do this with delay column? Ive been listening to a lot of classical music lately and there its called rubato I believe and such an effect when used subtly can really give some extra movement that often lacks in programmed/not recorded live music. Thanks 
For a single track, this won’t be easy.
For the whole song, you can put in tempo randomisations:
Add an LFO to the master track.
Select the random option.
Select in the devices “Mixer and Transport”, select as target parameter either LPB if you want rough time changes or BPM if you want gradual changes.
Set the amplitude, offset and frequency of changes to your need.
Now your song will continually perform different.
Thanks vV, looks like I`ll just have to use Reaper even more.
Just curious, how does that work in reaper?