kswapd0 takes my cpp program CPU usage to below 10%... How to overcome it?

I wrote a cpp program which reads several csv files and appends the data in a map >. The problem is that this data structure goes over 80% of my memory usage at some point, and then kswapd0 appears and takes my program CPU usage to belo 10%, which makes it extremely slow, given the nature of the program.

I do understand the nature of kswapd0, I know it wants to play around with disk and memory pagination, however I do still need my program to run!

Does anybody have a clue on how to overcome it?

The problem is not my program, I can ensure you that, because I separated the program in steps [basically grouping the files] and for some groups it doesn't happen, only for the real huge large groups take go over 85% of memory usage evoking kswapd0...