Will one mongoose collection slow down another?

I am running a site where I want users to be able to upload and store images. I realize that it is recommended to store images using an outside service such as amazon s3, however I do not want to have to pay for something like this at the moment.

The alternative I was told, is to create an API for image retrieval. It does not appear however, that mongoose allows for multiple database connections at the same time, so the easiest approach would just be to use a separate collection for my images.

My question is though, will using a separate image collection still slow down access to my other collections? Ideally, I am hoping it is separated so that even heavy image traffic will have no bearing on my other collections, but I am not sure if this is the case...

Can somebody clarify this for me?

Thanks

I understand that this is not a direct answer to your question, however IMHO if you're going to do something, do it right the first time and save your images into something like S3.

S3 has a free tier that you can use for 1 year. It will give you 5 gbs of space, 20 000 GET requests and 2000 uploads per month (honestly if you're going over that you can probably afford to pay for a small plan). You can read about AWS's free offerings here.