Raspberry Pi 3 for navigation

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Hi all, I'm using a Pi3 model B for simple mapping and navigation. But when I run gmapping package and run htop command, it showed that 4 cores are being used. I'm using the default parameters. Can you suggest some methods to utilize the memory, maybe some parameter tuning tips? And can you suggest any other appropriate computers for the navigation tasks? My budget is upto 300$. Thanks in advance.