Medium Multi LSM perf test degradation

The changes for the bulk load has caused the medium-multi-lsm.wtperf workload to drop by about 40%. I am able to reproduce this on my AWS HDD box too. Using the changeset 1f2e107 from http://build.wiredtiger.com:8080/job/wiredtiger-perf-med-multi-lsm/951/ and comparing against the first changeset in http://build.wiredtiger.com:8080/job/wiredtiger-perf-med-multi-lsm/952/, c82ed17, I see the same drop in the read/update portion of the test. My first guess would be that the compact after populate did not fully compact down to one chunk in the newer changeset. Compact in the old version took 334 seconds, new changeset it took 6 seconds.

Both runs of the test also exhibit drop outs in all throughput for 15-25 seconds at a time.