Hi Trinity,

The following KM may assist - KM34976 - Content Manager Minimum Network Requirements 

The required bandwidth mentioned in the KM isn't anything too extreme (MB/Sec), however, I've found the main thing to be the 'Latency' which is the time it takes for a bit of data to travel between the CM client, the workgroup server, to the database, and back (often referred to as the Round Trip Time and measured in Milliseconds instead of Megabytes / Gigabytes).

As CM can be a bit 'talkative' at times (lots of small requests going between the client and the server) - the longer this back and forwards chatter takes in Milliseconds (as the chatter can be quite small) can have a definite impact on the perceived speed of the application.

One of the places to look to get a very early idea on how a particular CM client will be to get the Performance Index

To do this, open CM, jump into Help -> About -> Setup Info and then double click Performance Index

Performance index - latency - double-click to produce a number that reflects how many times Content Manager can call the Workgroup Server per second.
The greater the number, the better the performance.

The higher the number the better. I find that once it drops down to be sub 20 that's when its quite noticeable and sluggish. Typically at home connections will perform slower than being in the office as the data has further to travel (higher 'Round Trip Time').

The reason for the slow performance is then harder to figure out. I'd first try to get a few different performance indexes from a few different locations (office 1, office 2, from home, via VPN) which will then give you an idea on where to focus the effort.

-Scotty