albe67 on "W3 Total Cache and Google webmaster tools"

Hi,
I installed the plugin on a site and then checked its speed with some tools like PageSpeedInsights for Chrome, PageSpeed for Firefox, Pingdom.
Everything was going well, the speed had greatly increased.
Then, checking the site with Google Webmaster Tools, I noticed that the page download time had enormously increased too!
So I deactivate the plugin and now the speed measured by GWT has become normal...
No other plugins were installed in the meanwhile.
How is it possible?
Thanks.
Alberto

https://wordpress.org/plugins/w3-total-cache/