This is just not true. The RAM consumed/used is not dependent on the bits being search...it comes down to your DP setting and how often you save the work file. I don't see your settings/flags when starting the program but you are using a very low -d setting or that plus using a long save to file time.
Sorry I forget tell use with old python version test on 256bit with set max 256bit that eat a lot of memory, that mean
For JeanLucPons Kangaroo it use low memory it work better other Kangaroo
recommend to use with GPU is better (CPU will full 100% resource )
if can have option for Kangaroo version OpenCL will be great