ID 270058 - Performance timers make Nuke perform much slower

Problem summary
Performance timers make Nuke perform much slower

Customer reported version
nuke.10.0v4

Customer reported platform
fedora

Steps to reproduce

1) Open Nuke

2) Create a CheckerBoard

3) Attach a LensDistortion node and set the Radial Distortion 1 to -0.01

4) View the LenDistroition node and playback the Nuke script, it renders fairly quickly.

5) In the script editor, run the command below:

nuke.startPerformanceTimers()

6) Clear the cache and playback the Viewer again, this time it takes much longer to render.

This also happens with other combinations of nodes, like basic animated 3D scenes or animated GridWarps.

Workaround
Disable the performance timers by using the below command:

nuke.stopPerformanceTimers()

Reproduced by support
This problem has been reproduced on:
Nuke 10.5v2 - Windows 10 - CentOS 6.8 - MacOSX 10.12
Nuke 10.5v1 - Windows 10
Nuke 10.0v6 - Windows 10
Nuke 10.0v1 - Windows 10
Nuke 9.0v9 - Windows 10
Nuke 9.0v1 - Windows 10
Nuke 8.0v7 - Windows 10 - CentOS 6.8 - MacOSX 10.12

Expected behaviour
For Nuke to render/playback at the same speed

Actual behaviour
It went from rendering at 10fps to 0.2 fps