Over on Ravelry, it's not that hard to find a discussion about knitting speed on the forums. It seems to be something of importance to a lot of knitters.
I must admit that I'm not overly concerned about my knitting speed now, but that could be because I've reached a skill level and speed with which I am content.
Out of interest, I timed myself the other day. On my current primary project (still the alpaca vest for Dad), which is a round of 246 stitches on 3.25mm needles (KnitPicks options, 60cm circular), I'm getting about 45 st per minute. At the moment, this project is plain stocking stitch with no shaping. I haven't timed myself on ribbing or moss stitch or on purling, but those would be significantly slower.
This is snail's pace compared to Miriam Tegels, who holds the world record at 118 st per minute. I have no idea what the average knitting speed is, and whether I'm faster or slower than other knitters with my amount of experience, but I've decided that it doesn't really matter.
I think what's much more important is how I feel about my own knitting speed. I used to get frustrated when I was much newer to knitting and it seemed to take forever to get to the end of a row. I knit English Style, or by throwing, and when I first learned, I did as many new knitters do, and held the right needle from above with my right hand, supporting it with my left fingers at the point and removing my right hand from the needle every time I made a stitch. It was very slow and my tension was all over the shop.
The person who had the most influence on how I actually form knitting stitches, and by extension, my tension and speed, was my beautiful Mother-in-law, a talented knitter herself, who made the simple observation that things might be better if I held the right needle from underneath, hooking my thumb under the needle, and not removing my hand to make the stitch, but rather putting the yarn round the needle by the action of straightening the first fingers of my right hand. Now that my knitting action has settled down into a pattern reinforced by years of use, it takes little effort and movement to make each stitch. I keep both elbows pinned to my sides, courtesy of many years knitting on crowded public transport, and there is virtually no movement of my wrists. I can knit for hours with little risk of cramping and about the only weird thing I've noticed about it is that while the first three fingers of my right hand are never completely straightened during the process, my pinky finger stays pointed straight out the whole time. There's no purpose to it, it's not involved in maintaining tension or anything like that, but I've tried to keep it bent out of the way and my hand starts hurting after less than a minute. So I've learned to ignore my silly pinky finger.
I taught myself to do Continental knitting once, in the interests of seeing if I could get any faster using that method. I can do the knit stitch, but I accept that I would need to go through a learning curve with it, and I'm happy enough with the speed I get using the method I do now, and I'm really proud of the even tension of my knitting, so the Continental knitting had never been something I've been prepared to persevere with enough to get good at it.
I think overall, for me at least, the most influential factor in how much I get done is not how fast I knit, but how much time I get to knit. I guess you could say that I'm fairly obsessed with knitting. I think if you got anyone who knows me to describe me, the fact that I knit would come up pretty quickly (probably just after the fact that I carry many more bags than seems sensible). It's really unusual for me not to have at least one project with me. At the moment I'm carrying two projects to work with me every day - Dad's alpaca vest, and since the vest is now too heavy to knit while I walk, a Wrap With Love square which is tiny enough to fit in my handbag. (Earlier today, when we could hear fire alarms and thought they were lower down in our building and we would need to evacuate, I made sure that I had the square with me so that I could knit while we waited to get back into the building. It turned out that the alarms were coming from the building next door, which I think was having a fire-drill). I knit at almost every chance I get - in the car (as a passenger only), in the bus, waiting in queues, at lunchtime, in the evening while watching TV or listening to Audio Books. I even have a device called an Easy Read, which I use to hold books while I knit. I once tried knitting in a work meeting when I needed to listen and contribute but not take notes, but people tend to think you're paying attention to your knitting rather than the meeting, even when you're holding your own in a fairly robust argument!
I think all that extra time I get to knit is what's making me a much more productive knitter now. Although I suppose that's easy to say when I knit twice as fast as some people I know. To the question "How do I speed up my knitting", all I can say is what worked for me, which was finding a technique which was comfortable, and practicing on getting good at forming the stitches well in a consistent rhythm, without concentrating on the actual speed. If the real question is "How do I get more done", then my answer is to knit every chance you get, and ensure you always have a project with you, so that you can take advantage of the knitting opportunities you weren't expecting.
(Of course, there are also the times when knitting is my meditation, when I concentrate on the feeling of making each stitch. At those times, speed is completely inconsequential, it's all about the rhythm and the flow and (dare I get all hippy-chick and everything), being at one with my knitting!)
The alpaca vest is now 35cm long, so I've only got 4cm to go until the armholes. (I haven't taken another photo so please just imagine yesterday's with an extra 4cm on it) Dad was blown away when I told him on the phone today that I had that much done. Don't you just love having someone who thinks you're a genius even when you're only knitting round and round in stocking stitch?