high disk write queue becomes very slow to drain if user is running views ( indexing is in progress )

Loaded 5 million docs using testrunner eperf: performance.eperf.EPerfClient.test_ept_mixed_original -p prefix=1,num_clients=1,batch=100,load_phase=1,access_phase=0,items=5000000,size=2,cur_items=3249129

Then the following to create/read/update/delete docs:
performance.eperf.EPerfClient.test_ept_mixed_original -p batch=1000,load_phase=0,access_phase=1,ratio_hot_gets=1.0,ratio_hot_sets=1.0,ratio_hot=0.5,ratio_misses=0.0,kind=nonjson,items=5000000,max_creates=5000000,num_clients=1,prefix=1,start_delay=0,size=2

(about 8k/sec), I noticed the write queues on servers would start to climb and ops/sec drop, with drain rate as low as 200 docs/sec. Doesn't seem to be timeout/retry behavior as know issue- MB-4693 as docs are draining, but at a very slow rate. (see screen attached) - will add diags if repro'd

Documenting behavior for DP4 as this code is being replaced.