It really depends on what you’re trying to view. After Effects is not like video editors, which play back using the original files. Instead AE stores each frame into the computer’s RAM and plays back from there. It used to be really obvious this was happening because you couldn’t preview anything until AE had gone frame by frame. These days it’s can do this on the fly, but it still puts your PC under pressure.
It might be worth clearing your cache out too.
In terms of freezing, it’s hard to says what the cause is, but if Chrome is freezing too, then it might be down to the GPU. Try using Mercury Software Only in the Project Settings (Found in the File menu). Something I find myself saying often is that while AE can use a graphics card, GPUs were built for gaming and they are optimised to ensure smooth, live gameplay. This optimisation sometimes brings them into conflict with software that wants every frame perfect no matter how long it takes.