@yashumittal if your images folder is 400MB, that means that because of the way jekyll generates your site, the file size would effectively be doubled, meaning 800MB. this checks out
I am not concerend that which sub-folder is taking a lot of space. Isn’t there is any alternative way to use Jekyll in the cloud itself. So, that we do not need to keep the copy on our local-machine.
Like other replies have already mentioned, static assets such as media files can increase the size of your website over time… and the solution is to host them on the Web somewhere and then link to those files via your templates.
This is not specific to Jekyll though, and can be applicable to any site on the WWW… thats the reason CDNs and various image- / video- hosting services exist.