KAISER: hiding the kernel from user space

> Most workloads that we have run show single-digit regressions. 5% is a good round number for what is typical.

A single change may not affect performance significantly (although 5% slow down is too much for my taste). But multiple changes can stack up over time. In the past this has been seen both for performance improving and for performance regression changes. A performance regression example is how compilers' performance regressed overtime (although since GCC 6 the trend has reversed). A performance improving example is sqlite.