File very big and very slow

I’m always drawing a boat, and every day I add parts.
The file is now 180 MB, I think a lot of great, or is this normal? However I work on one or two layers at a time. The processing speed on normal views is acceptable, but on views where a clipping plane is active is impossible to work.
Almost all surfaces have a texture .png.
There are tools of analysis to understand how much memory is being used by an object?
Some items are imported from other electronic files made available by the manufacturers; I have not imported directly these objects, but I’ve imported into a new file, saved in Rhino and then inserted as blocks or files.
In the attachments you see that the original file is .step 16.1 MB, while the same in .3dm has become 47.5 MB.


Nome modello: MacBook Pro
Identificatore modello: MacBookPro6,1
Nome processore: Intel Core i5
Velocità processore: 2,53 GHz
Numero di processori: 1
Numero totale di Core: 2
Cache L2 (per Core): 256 KB
Cache L3: 3 MB
Memoria: 4 GB
Velocità d’interconnessione processore: 4.8 GT/s
Versione Boot ROM: MBP61.0057.B0F
Versione SMC (sistema): 1.57f18

You mention attachments in your post, but I don’t see any attachments here. Did you mean to add attachments to this post so we can duplicate what you are reporting?

now my file is 340 MB, how can I send it?

you can upload it on the following page. Just make sure you reference Marlin as a recipient. (and 7z the file).