Apache 2.0 keeps pace with IIS on Windows servers but no performance gain on Linux seen.
For eWeek Labs preliminary tests of Apache 2.0 we used RadView Software
Ltd.s WebLoad 5.0 to create the test loads. Tests were based on scripted
access of static HTML pages. In all tests the web servers were in their
default configurations and were not tuned for performance.
Apache 2.0 performance on Windows 2000 Advanced Server

Apache 2.035 and IIS 5.0 were installed on Windows 2000 Advanced Server.
Given the fact that IIS is essentially the benchmark for performance on
Windows servers, Apache 2.0s ability to match it is very significant.
These results can be attributed to the improved design and native Windows
code for Apache 2.0.
Apache 2.0 performance on Red Hat Linux 7.2
At first glance the fact that Apache 2.0 didnt improve performance
on Linux may seem to be a disappointment. But the performance results are
still excellent. Also, since Linux treats threads the same as processes,
Apache 2.0s move to a thread-based model had little effect on performance.
However, users of Solaris, AIX, and other Unix systems, which suffered
from the use of processes in previous Apache versions, should see improved
performance and scalability.