Apache 2.2 with worker thread is a juggernaut but it's still not comparable to LiteSpeed with regards to serving static content.
Now for doing PHP as well it's more tricky with Apache as your best bet is FastCGI. If it's for a single site well it can be a pretty good performer. If you're looking at suexec as well you'll need pools for each user which can be a memory hog depending on the configuration. LSWS implementation is better from my testing with regards to all the PHP processes.
Also worth keeping in mind worker uses virtual memory. This can be devastating in some environments. For example a VPS you cannot run worker without first configuring the OS to handle the virtual memory. Otherwise you end up with the entire VPS memory being used by Apache.
So to summarize I bet with a lot of work to optimize for a specific environment you can get it close. Of course if I wanted to go this route I wouldn't even use the worker mpm I'd use the event one and assume I'm not using SSL or other features that are not supported on that mpm.