Hi,
This link may help:
https://helpx.adobe.com/photoshop/kb/photoshop-slow-lags.html
If the issue continues, you can try resetting the preferences of Photoshop using the steps mentioned here: https://adobe.ly/2Qzc0K3
Please backup your settings prior to resetting the preferences. You can check: https://adobe.ly/2vNz6FG
Thanks,
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