MagnetoDB's response time increases almost linearly as number of concurrent users goes up

MagnetoDB's response time increases almost linearly as number of concurrent users goes up, and CPU usage quickly jumps to close to 100%. See a sample query performance test result below:

Concurrent Users Avg Response Time (eventlet, ms) Avg Response Time (gevent, ms) Requests Per Second CPU Usage (%) CPU Usage (Cassandra)
1 8 7 105 65 6
2 15 13 116 75 6
3 21 19 125 87 6
6 40 36 134 93 6
12 84 74 137 99.9 7
25 170 158 135 100 7
50 358 316 136 100 7
100 700 651 134 100 7.2
200 1486 1320 135 100 7.5