When Sync'Em is syncing, you can select the "Open Sync'Em Engine Log" entry in the Sync'Em menu extra to monitor the syncing progress.

There are many factors that determine the speed of syncing — the following list is somewhat ordered, starting with the most important performance factors:

• an initial sync must sync and initialize everything and so will take a relatively long time:
• depending upon the factors below, allow from 1 to 4 seconds per item being sync'd ('though some systems will be faster and some will be slower)
• to see how Sync'Em is progressing, select the "Open Sync'Em Engine Log" entry in the Sync'Em menu extra
• note that accessing high-performance servers so Sync'Em can process transactions quickly will tend to use more processor resources, but for a shorter time — and Sync'Em is multi-threaded so it'll use multiple processors when available
• after an initial sync, only items that have been added/changed/deleted will be sync'd
• sync setups that sync a few information sources — e.g., an Exchange, Google and iCal calendar — will typically take less than a minute and not have any significant impact on system resources
• syncing with information sources that require OS X's Sync Services are slower and can consume significant CPU and memory resources:
• OS X's Sync Services provides the only full-featured Apple-approved interface to the Apple Address Book and iCal (and other resources) so Sync'Em must use Sync Services when syncing with Address Book and iCal
• the only Sync'Em operations that use noticeable system resources, especially CPU, are those where Sync Services are involved — it's Sync Services that's more resource-intensive
• OS X's Sync Services doesn't "scale" very well — e.g., at around 20,000 to 30,000 contact entries it gets non-linearly slower and becomes too slow to be practical (only Apple can fix this) — 'though it's true that most people don't have that many items of any kind!
• syncing Exchange-based information sources can require noticeable resources:
• in particular, syncing Exchange calendar events requires multiple transactions that require CPU resources
• the following general factors affect the overall/per-item syncing performance:
• the type and speed of processor — this is most noticeable for the phases that use OS X's Sync Services
• the faster the processor speed, the faster the processing (du-oh!)
• Sync'Em is highly multi-threaded so multiple processors helps, but primarily when the system is otherwise busy
• Intel-based systems, even of a comparable processor speed, are significantly faster than PowerPC-based systems
• Exchange and Google server performance — from the data we've seen, most Exchange servers seem quite fast and Google is legendary for normally having quick response
• the speed and latency of the network — normally not an issue, but slow wireless, VPN and/or proxy configurations can have a significant negative impact
• low available memory can have a noticeable effect, especially for the phases that use OS X's Sync Services — OS X's Sync Services can consume considerable memory when syncing many (i.e., thousands of) items and OS X, like any modern-day operating system, will seriously slow down if it's driven to "swap memory" on and off the disk (i.e., if it's using "virtual"/disk-based memory instead of RAM)

If you are experiencing conditions other than what would be implied by the above information, please review our article about OS X's Sync Services' corruption. As always, if you're having a performance (or other) issue, please create a support ticket and we'll help.