Videomaker – Learn video production and editing, camera reviews › Forums › Technique › Editing › Upgrade Advice › Hi Benjamin,
BruceMol is more than likely right. It's often the graphics card that slows down video previews. However, I would add that a HDD can also be the culprit. If your hard drive is taking a while to spin up, or has too much information written to it already (below 10% available space), the hard drive can slow the playback of your footage down. It usually doesn't slow it down to 10-15 fps, but it is feasible. To test this, you should try and move the footage for your project onto the SSD drive you have installed and see if that speeds up the fps. If it doesn't seem to help, it is definitely your video card.