rendering comp in ae in many times. so is there way to shorten the render time.

I looked at the project. I have a couple of comments and suggestions. The 01png is scaled to 24% in the main comp. It never gets to 100%, and the lines that make up the pattern at that scale are barely 1 pixel wide and moving. The opacity is also set to 94%. for the left and right images and only 10% for the middle image. Moving lines, especially slowly moving lines, should be about 2 pixels wide to avoid flicker and aliasing problems. These thin lines are also going to be adversely affected by MP4 compression. Color is compressed in blocks of 4 pixels. Thin lines are not going to hold up very well. Any raster image (png, jpg, video, any layer made of pixels) should be at or near 100% scale at some point in your project. AE has to calculate based on the original size of the image, so you are looking at more than eight times as many pixels as you need to for every instance of 01.png. O5.png is scaled to 15%. Never bigger. That is also adding to your render time. Both of those images need to be resized, and I would suggest that you thicken up the lines in 01.png.

The top adjustment layer is only adding transparency to the top and bottom of the frame. If you are delivering an MP4, it does not support transparency so all of those effects, the expressions, and the entire layer are doing nothing to change the final look of the final render except putting a blacker border on the black solid at the bottom of the comp.

The bottom layer, the black solid, also has a Tint effect applied to it. Tint will only change the black because there is no white on the layer, Tint increases render time a bit, so the most efficient way to get that color would be to change the color of the background solid.

I never saw one of the background elements come in front of the text layers or the photos of the bride and groom. There is no reason you could not render the background only, then just add the text layers. None at all. You could even use the Extended Grapics workspace and create MOGRT's for all of the text and the bride and groom photo, then add them to Premiere Pro and complete your motion graphic there. That's what I would do if I had a lot of these to do. Premiere Pro will render faster than After Effects. I would just use the Render Queue and use the High-Quality Output module default to render your background.

I hope this helps a bit.