Once imported, you can toggle a "Use Proxies" button in your editor to switch between the low-res "editing" files and the high-res "master" files instantly. Physical "Paper" Proxies
Use software like Adobe Premiere Pro or DaVinci Resolve to "transcode" your raw files into a more manageable format, like ProRes Proxy or DNxHR. FILMY PROXY
Many professional cameras (like Sony) can record low-res proxy files onto a secondary SD card simultaneously with the high-res footage. Once imported, you can toggle a "Use Proxies"