Hi there,
Thanks for reaching out. We are sorry for the trouble with Photoshop. We are here to help.
Where are these files stored, on an internal drive or an external drive? Does the lag happen with any specific set of files? Could you please share the system info of Photoshop from Help > System info > Share with us? Have you tried any troubleshooting steps?
- Go to Preferences > Performance > Advanced Settings and uncheck the 'GPU compositing' option.
- You can also optimize Camera Raw, which handles Raw images in Photoshop, by going to Photoshop > Preferences > Camera Raw > Performance > Uncheck Graphics processor and increasing the cache sizes
- Restart Photoshop.
- If disabling GPU compositing does not help, you can uncheck the 'Use Graphics Processor' and restart Photoshop.
Please check this series of suggestions related to software optimization and in-app changes you can do to optimize Photoshop's performance in this article, and please give this a detailed read through: https://helpx.adobe.com/photoshop/kb/optimize-photoshop-cc-performance.html
Let us know if this helps. We hope to hear from you soon.
Thanks!
Sameer K