Some more information.
I opened the Performance tab in Task Manager and observed the following:
 
If I open the LP MB or EQ dialog window, one of the cores (usually - but not always - the first core) increases to about 40-50% and cores 3, 5 and 8 show around 5% activity (very spikey, this is average). The bar on the left varies between 9 and 15%.
 
After two or three seconds, the laptop's cooling fan speeds up.
 
If I close the LP MB (or LP EQ)'s window (it is still enabled!), activity reduces way down to near 0% and the fan begins to slow down again.
 
I have also tried other effects, particularly Ozone 7 which is also known to be processor-hungry.
It also shows some activity but these are single spikes when I physically open the window or do something, then when I stop, activity goes down to near 0.
 
Please note I am only opening and closing the effects windows. I have not hit play yet.
And I am testing with a single audio track containing 10sec of silence with and one master bus, and with only one effect inserted at a time, in the Master bus.
 
I don't have the feeling this is due to a virus.
It seems these plugins have something with their front-ends that uses quite some processor power, just by being open.
 

jpetersen
Some more information.
I opened the Performance tab in Task Manager and observed the following:
 
If I open the LP MB or EQ dialog window, one of the cores (usually - but not always - the first core) increases to about 40-50% and cores 3, 5 and 8 show around 5% activity (very spikey, this is average). The bar on the left varies between 9 and 15%.
 
After two or three seconds, the laptop's cooling fan speeds up.
 
If I close the LP MB (or LP EQ)'s window (it is still enabled!), activity reduces way down to near 0% and the fan begins to slow down again.
 
I have also tried other effects, particularly Ozone 7 which is also known to be processor-hungry.
It also shows some activity but these are single spikes when I physically open the window or do something, then when I stop, activity goes down to near 0.
 
Please note I am only opening and closing the effects windows. I have not hit play yet.
And I am testing with a single audio track containing 10sec of silence with and one master bus, and with only one effect inserted at a time, in the Master bus.
 
I don't have the feeling this is due to a virus.
It seems these plugins have something with their front-ends that uses quite some processor power, just by being open.
 

indeed that sounds like classic inefficient gui code, especially closing the window reduces cpu to ~0%

I have the same issue as the OP. There is something going on here.

Just to confirm. LP MB, inserted into Master bus, transport stop (but that does not make any difference), in % of CPU used as displayed by resource monitor:
DISABLED - NO GUI - 0%
DISABLED - GUI - 10%
DISABLED - GUI, Expert settings open - 18%
ENABLED - NO GUI - 5%
ENABLED - GUI - 16%
ENABLED - GUI, Expert settings open - 23%
 
And that is with Analyzer:Fast, Precision:Non Linear.
 
For comparison, LP-64, enabled, GUI, - ~0%
 
Conclusions:
a) LP does something once enabled, that "something" is moderately CPU heavy
b) LP GUI is not written by programmers...
 
EDIT: ProChannel EQ, in FlyOut mode, during play - ~0%. CW knows how to write GUI

To be more detailed about it, under certain conditions the stop button ceases to work with just these LP plugins. I do not have this issue with other plugins which are CPU inventive or do look ahead. Remove these LP plugins and the issue goes away. I have no viruses or malware, and a very good Focusrite Scarlett interface with latest ASIO drivers. I normally have very good performance, my PC specs are pretty good.

I don't know the technical details on how this may be caused, but I know something is up as three of us now have similar issues with the stop button and these plugins.

azslow3
Just to confirm. LP MB, inserted into Master bus, transport stop (but that does not make any difference), in % of CPU used as displayed by resource monitor:
DISABLED - NO GUI - 0%
DISABLED - GUI - 10%
DISABLED - GUI, Expert settings open - 18%
ENABLED - NO GUI - 5%
ENABLED - GUI - 16%
ENABLED - GUI, Expert settings open - 23%
 
And that is with Analyzer:Fast, Precision:Non Linear.
 
For comparison, LP-64, enabled, GUI, - ~0%
 
Conclusions:
a) LP does something once enabled, that "something" is moderately CPU heavy
b) LP GUI is not written by programmers...
 
EDIT: ProChannel EQ, in FlyOut mode, during play - ~0%. CW knows how to write GUI

 
WOW! You are right! When I opened the Expert window, CPU cores 1, 3 and 5 shot up and are hitting 100%!
And the cooling fan has just increased another notch in speed! Crazy!

When you say 0%, 10% etc... which core are you looking at?

jpetersen
When you say 0%, 10% etc... which core are you looking at?

As you can see in my spec, I have just 2 cores ;)
But I am looking at "CPU consumption" for the program, in numbers.
 
I guess big part of the issue some users have and other do not come from the not extremely real time aware intercommunications within PC. I mean for how long the hardware is blocked during CPU/RAM/GPU depends from near everything inside the computer, motherboard, graphic card and drivers. Since CW say they use OpenGL and we observe huge (for computer) CPU load, probably there is continuous  hammering the system bus. ASIO audio drivers are not build to tolerate any delays, so one single buffer underrun can produce the whole set of strange effects, from drop outs till "hanging" transport.
 
Just curious, when you see "no stop" effect, if you press "Audio/MIDI reset" button, what happens with audio and the button?

Transport stops and the Now cursor jumps back to the beginning.
Spacebar also works.
In my case, only the Stop button in the Transport fails to light up and react to clicks.
 
OK, I think we have this one nailed, although this looks more like a case of poor programming rather than a bug as such.
It is reported und the number CWBRN-50523
 
Thanks very much for the help!