One of the method you can use it is:
1. Select “Ripple Edit Tool”.
2. Zoom out and select all needed clips.
3. On numerical keyboard write +10 and press NumPad Enter.
4. Then press SHIFT+T (Toggle Trim Type) and it will change selection to another side of clip.
5. Enter -10 on numerical keyboard and press NumPad Enter.
That’s all. You will add handles to all the clips you need. Maybe IN handle for the first clip you will need to change manually.
Also I’ve noticed, that if you will zoom in to max before processing handles it will increase speed of work of Premiere.