The allowable file size and number of polygons that will be operable in a BIMx file is heavily dependent on the device the file will be read from. I have saved out several files of varying size/polygon count and tested them on different devices.
The file I used to start from was one of our projects running efficiently at 420,000 total polygons with all layers on. I then tested the limits by copying elements to incrementally increased polygon counts. All files were saved from a solo (PLN) project, so AC file sizes were significantly less than our average Teamwork file size.
The tests files ran as follows:
Test 1 : 418,000 Polygons : AC File Size 290Mb : BIMx File Size 34Mb
Test 2 : 1 Million Polygons : AC File Size 290Mb : BIMx File Size 65Mb
Test 3 : 3 Million Polygons : AC File Size 294Mb : BIMx File Size 173Mb
Test 4 : 6 Million Polygons : AC File Size 311Mb : BIMx File Size 335Mb
Test5 : 10 Million Polygons : AC File Size 331Mb : BIMx File Size 558Mb
Test6 : 15 Million Polygons : AC File Size 383Mb : BIMx File Size NA
Test 6 failed to save a BIMx after repeated (and lengthy) attempts. I opened each of the BIMx files on various devices. On any of the current iMacs in the office, the 550Mb BIMx file should run sufficiently. All BIMx files were tested with standard settings; shadows on, SSAO on, shadow filtering on, rendered using Headlight mode. I did not run Global Illumination on any test. Results for other devices are as follows:
iPad : Ran up to test 5 efficiently
Mac Book (Old) : Ran up to test 4 efficiently on laptop only, test 3 on screen share to conference room monitor
Mac Book (New) : Ran up to test 5 efficiently on laptop only, test 5 ran satisfactorily (minor navigation choppiness) when connected to the conference room monitor. Test 4 ran efficiently both on the lap top only and the conference room monitor.
As the BIM manual outlines, tests should be made for specific BIMx files well in advance using the device, display and file that will be presented. Check for model content, surface translation and file operation at least 6 hours to 1 day before a formal presentation. See the BIM Manual > External Content > BIMx Optimization for more information on BIMx standards and settings.