To a large extent, Fraps is professional to record games. But some problems indeed exist in using it. For example, as you’ve mentioned above, it lags the computer severely because it occupies large disk space and its outputs are in large file size. Besides, it is not free and outputs videos with watermarks.
Fortunately, all of these problems can be perfectly solved by using Apowersoft Free Online Screen Recorder. In terms of lagging PC, this free full screen recorder does well as it is running online and does not entail any installation of other software. Thus, you don’t need to concern the speed of your PC at all. In addition, it has no time limits so you can record as long as you want.
Now I will show you how to use this app to record games in full screen in details.
1. Enter the website, and click Start Recording button.
You’ll see an intuitive interface which is very simple to use. Even if you are a green hand, you could quickly handle it well.

2. Preset the Audio Input as you like.
This full screen recorder allows you to record video with audio from system sound, microphone, or both of them synchronously. Therefore, during the process of recording full screen games, you are able to capture your own voice from microphone to make a commentary.

3. Choose Full Screen to start recording.

Very easy, right?
Tips: You may find that when you want to pause or stop recording, you have to exist full screen to click the buttons. No worries, this screen recorder offers hotkeys to you. Just click the Tools button on the interface, next, tap Options, then, you can preset them according to your own habits.
If you still have no idea how to record full screen games, a demo video is provided to teach you.