Each time Photoshop start, all plug-ins (necessary or unnecessary) also load with Photoshop. You can prevent unnecessary plug-ins by loading thus reduce start up time.
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Navigate to C:\program files (assuming ‘C’ is your installed directory)\Adobe. Open the directory. Here you can see folder named ‘plug-ins’. Within this folder you find the plug in files, all of which loaded each time Photoshop started.
You can disable plug-ins which you scarcely use. To do this simply edits the name of the files or folders containing plug-ins and insert a tilde (~) before each name. You can always re-enable the plug-ins by deleting the symbol ‘~’.