Do you have any source for this? While logic suggests that they should (but perhaps only very slightly) I think InnoDD has got a lot of more optimization work than any other engine.

A benchmark from Oracle shows InnoDB as being much faster on a read-only workload.

http://www.oracle.com/partners/en/knowledge-zone/mysql-5-5-i...

EDIT: By the way the locks are table level in MyISAM and Memory.