If you understand throughput as the effective number of transactions that users experience per second from your hardware software stack then you would ideally want maximum possible transactions per second from your setup.
We understand that any software stack would ultimately use CPU cycles to process all these transactions. Hence, the transactions per second delivered per CPU cycle is the true measure of the performance of your system.
Ideally we should be measuring throughput of a system and how many CPU cycles does it take to deliver that throughput. Inefficient code would spend many more CPU cycles to deliver X number of transactions per second aka tps. Optimized and efficient code would deliver the same transactions per second using far lesser CPU cycles.
Thus a good measure of system performance is throughput per CPU usage. This is the number to watch.