I have Pro but my load/CPU has not improved

Really? Perform the procedure described on this page.

If the comparison you make against the proenabled and prodisabled stats files shows a reduction in CPU when the Pro options are enabled, then your CPU utilisation by Check WMI Plus is working and Pro is doing what it was intended to do.

Using Cached WMI Responses

If you still think your CPU/load has not changed, then it is something else. There is another Check WMI Plus test you can run, but you need to do this other test under controlled circumstances since it will cause Check WMI Plus checks to give errors and hence generate Nagios alerts. The test removes all WMI calls and just uses the last data retrieved by WMI in place of any future WMI calls. Obviously, this makes all responses from Check WMI Plus false and will make any checks that rely on 2 data points generate an error.

The benefit of this test is as follows: WMI calls take a long time. They are most often the longest part of the elapsed time of the plugin execution. The longer the plugin is running the longer it stays in the run queue (whilst waiting for IO) and hence potentially increases what you see as load figures even if CPU is not being consumed. If the plugin does not have to wait for WMI calls it can complete much quicker. This test will enable you to clearly see if the WMI calls are making your load appear high.

To perform this test, make the following change in your Conf file:

Remember to change the setting back!

Disable Check WMI Plus

Try taking Check WMI Plus out of the equation all together. Rename the plugin, put an exit; as the second line of the plugin or something similar to make it do nothing.
See what that does to your load/CPU.

Its Still a Problem for Me

If you are no longer running any Check WMI Plus checks and you still have high CPU/Load then it is clearly something else.
You'll have to eliminate other possibilities just like we eliminated Check WMI Plus.

Capturing a Machine Performance Snapshot

This may be useful to record performance differences as you make changes.
During each of the collection cycles, run "top", halfway into the top session, press "1" to add CPU details. For each of the top sessions you run, video the screen using your phone, a video camera or preferably some screen grab software. Save the video with a meaningful name. You normally only need a session length of 1 minute or so to get a good feeling of how the system is performing.