Windows 10: Toshiba Laptop has become really laggy

You may not have been aware, but until 19th May there was a problem with DISM's RestoreHealth for 15063 failing with the error 'source not found'. This error was corrected by Microsoft, not by updating your Windows, but by providing a new version of the packages for DISM to download and complete the repairs successfully. Your long wait for completion may well have been due to a slow download of the updated packages DISM required.

Creators update component store shows corruption but unable to repair

 

Many people will use their computer in selective start up (very close to clean boot) to have the fastest boot times and have task manager columns with the lowest percentage numbers. The items that are always used are checked and everything else is off on boot.
Windows 10 Performance and Install Integrity Checklist - Microsoft Community

In your situation there is a noticeable difference between normal startup and clean boot. To find the application(s) that is/are impacting performance you can now perform the following steps:

Open msconfig and count the number of non-Microsoft items. If there are 32 then recheck 1/2 of them so that there are 16 checked and 16 unchecked. Reboot and check the performance. Return to msconfig and uncheck the items that were just checked and check the 16 rows that were unchecked. Now compare the performance. At this time you know how the system performs with 32 boxes unchecked, one group of 16 boxes checked, and another group of 16 boxes checked. You now know which group of 16 impacts the performance in a negative way and which group of 16 has no or little impact on performance. this process is repeated.
The group that had 16 boxes checked that had a negative impact on performance is changed to 8 checked boxes and 8 unchecked boxes. The process is repeated over and over again cutting in 1/2 until the misbehaving application is identified. Then that application can be uninstalled and reinstalled to see if the computer performs better. If not the application can be either completely uninstalled or left installed and unchecked so that it does not negatively impact performance.