Faster simple bar for perf test

[lrq3000]

Added trick described in 0346a4a to the simple bar in perf test. Didn't test if the bar was faster, but since this is exactly the same scenario it should also improve the speed.

[coveralls]

Coverage remained the same at 90.776% when pulling 692b644 on faster-perf-test into 02cbd9c on master.

[lrq3000]

Ok I'm done here. I don't want to enhance this simple_bar further because it should not become a duplicate of tqdm_bare, so any enhancement will go exclusively there (except if it's a performance enhancement, but I doubt we can do much more than that).

[coveralls]

Coverage remained the same at 90.776% when pulling 66aa8d2 on faster-perf-test into 02cbd9c on master.

[codecov-io]

Current coverage is 90.56% (diff: 100%)

Merging #257 into master will not change coverage

@@             master       #257   diff @@
==========================================
  Files             7          7          
  Lines           477        477          
  Methods           0          0          
  Messages          0          0          
  Branches         85         85          
==========================================
  Hits            432        432          
  Misses           44         44          
  Partials          1          1          

Powered by Codecov. Last update 02cbd9c...16bbb21

[coveralls]

Coverage remained the same at 90.776% when pulling 16bbb21 on faster-perf-test into 02cbd9c on master.