If your computer can't handle it you can create a folder to put images in, that would be for each frame of animation. Krita is a good program and it is free, and you download it from their site, so no viruses. GIMP has a great pencil tool for pixel art, and has a great selection of useful filters. It's possible to export into a gif straight from the program and it's not much of a hassle. It's not commonly mentioned, but it's possible to create animations using GIMP.

Unfortunately the program doesn't instantly convert your animation into a gif when exporting and there is a strong limit on the number of animation frames that can be combined in their online frame-connector AlpacaDouga. It has onion skins and each layer is a frame. Highly recommended, it has a nice, simple interface and is extremely straightforward in its animation layout. If you're trying to create simple animations with a solid drawing program, FireAlpaca would be a good way to go. Unfortunately It may crash when overwhelmed and some users have issues with it. It's great for intricate and detailed work if you're trying to create something sophisticated, and a number of useful tools that goes beyond what can be spotted at a glance. It's not perfect as setting it up the animation export system may be a hassle, but it has an amazing animation layout and layer system - it has onion skins, it's possible to play audio over animations in the program, and you have a timeline rather than the standard 'each layer is a frame' system. I've made two relatively long animations in it and many shorter ones. I'm a huge fan of Krita I've been using it for years for a variety of projects. (Unless you download them off of some shady website) Hello, I've been animating for a long time, and here are my top three choices for FREE 2D animation - related programs with no viruses.

Play animation in firealpaca