Depending on the laptop it might be possible to install a second memory chip or remove and replace the one that's installed (some, especially smaller laptops, have the chip soldered in place and you can't change it). This might help the pauses changing between different files as it might not have enough memory to play with.
Other things you can do include replacing the HDD with a solid state drive, this will dramatically speed up the start up time when you switch on the laptop and can speed up starting programs as well. This can be quite easy if you buy one with a lead and software to clone your existing drive onto the new one before you install it. Also, if you have all the software and drivers available to reinstall, backing up all your data, formatting the HDD and reinstalling Windows (assuming that's what you have) and then all the software and then copying your data back on can help, but is a pain.
Of these adding/replacing a memory chip will probably be cheapest, easiest and have the most visible effect.