On the December-17 YCSB performance build we saw an 8% regression (29056 vs 26712) compared to the previous December-15 build for the "Basic Standard Test Throughput" metric, against the WiredTiger develop branch on Linux. On Windows it had an even sharper 33% regression (22665 vs 15076) for the same metric.

The list of WT tickets merged between the December-15 and December-17 builds are:

1. Revert "WT-4968 remove all committed and connection level commit timestamps (#5040)" (#5053) (commit: 2b7cf1e) (detail / githubweb)
2. WT-5314 For python tests, don't try to load extensions with empty names (#5049) (commit: b41d10a) (detail / githubweb)
3. WT-5257 add assert to hopefully silence coverity (and for actual errors) (#5046) (commit: 2d2e285) (detail / githubweb)
4. WT-5139 Incremental backup API (#4993) (commit: 77f9aeb) (detail / githubweb)