Table_open_cache scalability issues

Hello,

in spite of recent effors, table_open_cache still seems to be hit by negative scalability. I ran the following benchmark tests:

• SET GLOBAL table_open_cache = 64
• Create 10,000 MyISAM Tables with a single integer
• Access all tables in a loop
• SET GLOBAL table_open_cache = 4000
• Access all tables in a loop

Results are the following:
Table creation: 4s (sync_frm=0)
SELECT, Table_open_cache=64: 1.696519199s
SELECT, Table_open_cache=4000: 5.946816624s

The results are quite consistent and performance seems to decrease linearly.

My biggest concern is that MariaDB 5.5.40 is 2x faster with this test:

Selecting from tables with default cache (64)
Time: 1.536537015s
Selecting from tables with extended cache (4000)
Time: 2.798534456s

The only good news is that MySQL 5.6 seems to do worse with this test, with 6s and 9s respectively.