2. Edit From Smart Previews
Smart Previews are like magic. Lightroom can build smaller versions of your images in your Lightroom catalog so that you can keep editing when you disconnect.
This is really useful for laptop users with huge image libraries on external drives. When it’s time to leave your hard drive at home and hit the road, you can keep editing thanks to Smart Preview.
Adobe recently added another key use for Smart Previews: you can edit from them and enjoy a performance increase. Here’s how it works: Smart Previews are smaller files than the original RAW images. They’re quicker to work from, even when you have access to the original, full-resolution images. We can make Lightroom use the Smart Previews while editing instead of the originals
Go to the Lightroom Preferences and choose the Performance tab. Tick the Use Smart Previews… box to enable this feature and speed up your editing.
To make Lightroom edit from the Smart Previews, access the Preferences, and choose the Performance tab. Check the box that reads Use Smart Previews instead of Originals for image editing to turn this option on.