It appears that configuration parsing is resulting in a significant overhead when calling cursor->bound this has resulted in regressions being seen in workloads such as linkbench.

A basic WT reproducer was created to mimic the MongoDB workload that was seeing the regression. It had the following result:

(20:50)(bounded_cursor_perf)$ ./bounded_cursor_perf
Running test command: ./bounded_cursor_perf
prefix_search:
load: 1780
update: 1816
bounded_cursor:
load: 2507
update: 2340

As we can see the performance regression was in the ballpark of 30%. This is surprisingly high. Using the linux perf tool to profile the workload it was clear that the cursor->bound call was signficantly more expensive than the cursor->reconfigure called used by the prefix_search implementation.

A quick fix was implemented in the cursor->bound API to reduce the overhead of configuration parsing and the following result was taken from the reproducer:

(11:36)(bounded_cursor_perf)$ ./bounded_cursor_perf
Running test command: ./bounded_cursor_perf
prefix_search:
load: 1884
update: 1839
bounded_cursor:
load: 1994
update: 1818

The same improvement was seen in the repro.js mongodb reproducer that was created in SERVER-56509.

This work in this ticket is to take the adhoc fix in cursor->bound and formalize it.