Large models will not open in the workshop on my computer. They will load fine up until the loading assets stage, at the end of this stage the webpage crashes, and chrome tells me that something went wrong when displaying the webpage. I am not sure if this is just my old computer not being able to handle all of the 3D models, as the model I am trying to open (the Ninjago Movie Destiny's Bounty) is 6.4 megabytes, but if this is something that is happening to other people as well it may be a problem with large models in the workshop.
It is probably due to your computer specs. Browsers normally crash when the scene is too heavy for the graphic card.
File size doesn't really reflect the complexity of a model.
What you can try is to open the workshop and set all the viewport options to the minimum - mainly no edges and no logo on studs - Then open the model.