Here are a few interesting Q&A gathered from the BACnet mailing list.

Does anyone have experience as to adjusting the max_info_frames to increase overall network speed?
 
Would it matter if the devices do NOT support read_property_multiple?

- Bob Kline

Adjusting max_info_frames can improve performance – or make it worse.
 
If the link has a “system controller” who initiates most requests (read a bunch, write a bunch, repeat), then increasing that device’s max_info_frames is usually a good idea, to avoid needing to wait for a token pass that no one else will use anyway.
 
Similarly, a router from IP to MS/TP should usually have a reasonably large max_info_frames, since the router often represents multiple devices on some other network.
 
BUT: if you go TOO large, then one device can dominate the link, slowing the token rotation time, so that everyone else will have to wait longer to send their own requests.  And a gigabit IP device can ALWAYS swamp a 76800 baud MS/TP link
 
- John Hartman