Video has huge file size and takes forever to render

[#1]

I made a simple Twitch transition in After Effects. It's a 2 second video and only has one effect (CC Light Sweep). The problem im having is that the estimated file size in Adobe Media Encoder is 136 mb with a hour and ten minute render time in WebM (Im watching a YouTube tutorial on how to make a transition and it says to use WebM to make it run better on stream). Im pretty sure the file size should be about 4 mb. When I put it in H.264 it goes to 369 mb. Any ideas? Ive done this before and had no problems so I don't know what the issue is. Hope someone can help.

[#2]

I made a simple Twitch transition in After Effects. It's a 2 second video and only has one effect (CC Light Sweep). The problem im having is that the estimated file size in Adobe Media Encoder is 136 mb with a hour and ten minute render time in WebM (Im watching a YouTube tutorial on how to make a transition and it says to use WebM to make it run better on stream). Im pretty sure the file size should be about 4 mb. When I put it in H.264 it goes to 369 mb. Any ideas? Ive done this before and had no problems so I don't know what the issue is. Hope someone can help.

[#3]

by the way the video is 1280x720 30 fps 

[#4 · Accepted solution]

Ok I found the problem/problems. So the problem was that I had the 2 second transition on a 5 minute timeline/work space (I don't know what its called). So what was happening was that the 2 second transition would play and there would be 4:58 of black screen. So all I had to do was ctrl+k to change the length of the project and it got fixed.