DISM & SFC are a 'one-two' punch so run according to this:
https://support.microsoft.com/en-us/help/4026529/windows-10-using-system-file-checker
If that does not help, it is time to locate the testing utility for the HDD and the SSD and to test them (download from manufacturer's website). Please report results and provide manufacturer, model and detail on how much is stored on the drives. Look for firmware and driver updates as well.
If not fixed, run Malwarebytes (free edition).
Check Device Manager for errors.
Check Reliability Monitor for failures and warnings
If that doesn't help AND both games and search have lagging issue still, try Search Troubleshooter: Start > Settings > Update & security > Troubleshoot, then Click Search and Indexing and Click Run the Troubleshooter - describe problem as "lags"
If that has not corrected the issue, try Task Manager - sort by CPU use - and run in a window while running game or search in another window. When you note a lag, check what is running heavily in Task Manager.
Still stumped? Well, I am too. So then confirm you have backups of your data files and license keys to all your programs, because the next step often leads to a clean install of a fresh copy of Windows. Alternate might be to install fresh windows on new SSD...