Help improving performance

My laptop has 2gb on ram and intel I3 2.4 GHZ, also 64 bit operating system running windows 7. I'm working on a multiplayer game and whenever i build the game and start the match my graphic controller starts going on and off and then suddenly my laptop will crash and restart(note: i'm also running the game in Unity itself so i can test the multiplayer feature with myself)

So basically what i want to know if there is anything i can do to improve my performance on my laptop so i can finish this game. it doesn't matter if i need to lower the game quality itself as long as i can working on the coding side, i'll raise the quality later.

Also:

1. I can't afford a new pc at the moment

2. I'm using the classic theme, so all of those fancy stuff are disabled.

3. I've already tried when building the game to set the quality to fastest

4. My graphic controller has already been updated to the latest version

5. I'm fairly new to Unity