Popular Windows BitTorrent client uTorrent just released its first stable 1.0 client for Mac yesterday, but most users are sceptical about leaving Mac favourite Transmission (which recently reached the 2.0 milestone). Here's how the two stack up against one another.
Where uTorrent Shines
Very surprisingly, uTorrent is just as lightweight as Transmission when Transmission works properly, and much more so when Transmission starts eating up resources for no reason. Even with the new, speed-oriented version of Transmission, I'm still noticing a lot of random jumps in CPU usage on one of my machines — sometimes it'll be fine and take up less than 2 per cent, and others it'll be up to 50 per cent and stay there for a good long while. Note that this doesn't seem to be as widespread as it used to be, but it's still pretty rampant on my system, and a few other users are having this issue too. It must be interfering with another app, though I couldn't figure out what. It's also worth noting that I haven't seen any of the egregious memory leaks that Transmission used to have, so RAM usage is about equal.
But this section is about uTorrent, after all, so here's the lowdown: this thing is light. It may not look like it with that giant window full of downloads and statistics, but on my machine uTorrent hovered around 4 or 5 per cent of CPU usage, and only took up a mere 50MB of RAM. It's not quite as light as Transmission (which can sometimes get down to 1 per cent CPU usage), but it's certainly lower than something like Vuze — and the difference is usually negligible.
Note that if you aren't having problems with Transmission, the two are, for all intents and purposes, equal in the realm of performance. Transmission users unhappy with CPU or memory leaks should definitely give uTorrent a shot, but if Transmission works fine for you, performance alone is no reason to switch (although by the same token, it isn't reason enough alone to stay with Transmission either).
Interface (for Stats-Hungry Users)
Click on the image for a closer look.
If you find yourself with a high number of transfers at any given time, you may find uTorrent's UI more to your liking than Transmission's. uTorrent sports a pretty nice 3-pane interface, one large pane giving you a list of your transfers and some simple stats like percent completed, speed and active peers, and the other providing a number of tabs with pretty much any other stats you could possibly want. In Transmission, you have to open these up in a separate window, which isn't ideal if you're likely to be constantly checking them. And, if you have a lot of transfers, it's nice to have them all condensed so you can see and manipulate them all at once, as well as narrow them down by status in the sidebar (whereas Transmission's list takes up a bit more space if you have a lot of transfers).
Where Transmission Keeps it in High Gear
Advanced File Management Features
One thing still missing from uTorrent is the ability to sort files into different download locations automatically by group, as well as group certain files together in the UI. Transmission does this pretty well, allowing you to filter transfers by tracker, comment, torrent name or name of any enclosed file. Thus, you could filter torrents that contained movie files (by filtering files that contained .avi, .mkv, etc. in their file names) into your Movies folder and music files into your Music folder, for example. You can also colour-code and sort them from within the UI, which is pretty handy.
Interface (for Minimalists)
Of course, group sorting is just about as customisable as Transmission's UI gets. This isn't to say that the UI is bad; a lot of users (including me, most of the time) prefer it. Its window can be as large or as tiny as you want, and without a bunch of statistics and sidebars taking up space it can sit quietly in the corner and not bother you. In fact, you can even close the window entirely if you don't care about monitoring your individual torrents, since Transmission's dock icon shows your upload and download speed at any given time. Plus if you ever do want to view more statistics on your speed, swarm or individual files, you can do so by clicking the info button. Again, it'll pop up in a new window, but if you only need it once in a while, that's probably preferable for you. If you're more of a minimalist as far as UIs go, Transmission has a pretty clear edge.
This is one of those features that is a make-it-or-break-it deal for lots of users: you can monitor your transfers from a web UI with Transmission. The web UI looks pretty great, too, with a very similar interface to Transmission's app window, allowing you to open new torrents for download and view in depth statistics on each transfer. Furthermore, you can password-protect the web UI for your home computer's instance of Transmission, as well as only allow certain IP addresses to access it. If you want to monitor your usage from work, home or anywhere else, Transmission is the only choice here.
Speed Limit Mode
If you have specific times of the day that you'd rather not give all your bandwidth to Transmission, you can enable speed limit mode, which is a separate set of speed preferences than the defaults. Thus you could set your defaults as whatever you want (whether unlimited or limited), and then set speed limit mode to limit them even further. You can enable speed limit mode at any time with the click of a button, or schedule it to turn on and off at specific times of the day (so you give all your bandwidth to Transmission when you're asleep, for example). You can always edit your speed preferences in uTorrent, but again, Transmission is king when it comes to automating the process.
If you are on a firewalled network, such as one at your work or school, you can sometimes use a proxy server to bypass the firewall that is likely blocking BitTorrent usage. Transmission supports this, allowing you to specify the server, port and any authentication you need to access it. uTorrent does not yet have this feature.
Where They're on the Same Playing Field
Yes, I know this was already in another category — but like I said before, if you aren't having any problems with Transmission leaking CPU or memory usage, the two are pretty comparable in terms of performance. When Transmission was working the way it should for me, it fluctuated between 1 and 4 per cent CPU usage, with around 40 or 50 MB of RAM, the same as uTorrent. The bottom line is this: If you're having issues with Transmission still, the performance edge goes to uTorrent. If you're not, it's mostly a tie.
Most of the other connection preferences like encryption, automatic port randomisation and mapping, PEX and DHT are available in both clients. These have become staples as of late in most clients, so it's not that surprising, but worth mentioning since if it was missing in one, that would require you to go back to manually mapping those ports, which would be quite an inconvenience (I don't even think I remember how to do it).
The Bottom Line
If you need some more advanced features like a web interface, or you like to automate the whole process as far as sorting files or scheduling speed limits, Transmission is the clear choice. If not, though, it's pretty open to your personal preference. Minimalists will like Transmission's non-intrusive UI, and obsessive, stats-hungry downloaders will like uTorrent's 3-pane, multi-tab interface to keep an eye on things. Also keep in mind that uTorrent is still a baby on the Mac. The more mature Windows version does have a lot of the features we list as missing here, such as a web UI or a speed limit mode, so we hope that eventually these will make it to the Mac version as they continue to develop it.
Of course, this list isn't completely exhaustive, and everyone has their own features that are essential to their download process. So if we've left out your favourite feature, be sure to share which client you like best and why in the comments.