I've just finished a 45 minutes long sitting, and it was for the second time that I managed to get myself up to speed. I was able to note 4-5 things in one second(OK maybe that's kindof slow for others but I am a beginner), and although that speed wasn't consistent during the practice, I never got lost or caught up in anything.

As oppsed to my last time success, keeping myself in this state was not completely effortless, but it was kind of easy.

I am struggling with integrating a steady object into my meditation. I use the breath at the beginning of the sitting but as soon as I get faster I find concentrating to the breath not only useless, but a hindrace, because if I bring my focus to the breath, my noting speed drops. I can note the individual breath awarenesses, but not paying attention to the other sensations that arise my mind becomes dull and slow. 

Isn't it better to observe the continous arisings of all the sensations rather than focusing on one, like the breath and ignoring the rest?

Different people have success with one or the other, but not usually both, so you have to try each method and decide which one to stick with. You really should stick with the one that suits you best, based on your experience and not someone else's.

Good luck!

Thank you for your answer. It seems to me that direct focus on one object is not that effective for me. By the way, I don't really understand how focusing on one object can be regarded as vipassana practice. Paying attention only to your breath would mean that all the multitudes of arisings are igonored right? So wouldn't it be more like a samatha practice? The only thing I can think of is whether there are people with minds so calm that they have much less arisings so they able to keep steady focus on their breath without having to ignore the mutitudes of other arisings. 

 
What if you were paying attention to the arising and passing away of that one object? Watch it flutter. Watch it appear and disappear. How fast it that happening? Can you see the arising clearly? The passing away?

I can only catch the arisings. But a few days ago I tried walking meditation and I was able to catch the whole life cycle of some sensations., however, the experience was not a steady one. Just saw some sensations randomly popping up, but I was able to see them in full length. But it makes me think now that I might need to improve my concentration with dedicated samatha practice.

Yesterday's sitting was so much better than the previous ones. I didn't push myself to note every sensation, I was kind of trying to do it in a pace that is easier to keep up with at the current stage of my development. I didn't care at all when I missed some. I noted once or twice at max a second. It was so much better. My mind got way much calmer than it used to get any time before. The neither not too fast nor not too slow noting kind of anchros the mind. Now I think that I found the right way of doing the prectice.

I also noticed after a while that the sensations that did not get noted straight away queued up in the memory for subsequent noting. I am not sure if it is a good thing. On one hand, it seems a natural working of the mind to store those sensations for a short while, but on the other hand, why should I bother noting them rather than focusing on present phenomena? The question I need an answer for is whether noting these past sensations in the memory is the consequnce of me not letting go and intentionally trying to keep the past in focus or is it a natural proclivity of the mind to push the past into the present? Either way, all of those sensations in the memory seem to have already been noted when they arose in the mind, it's just the "tags" like hearing, hot, sitting etc... that were not applied to them at that time. And the mind is just doing the job it thinks it has to do: applying the tags. From the watcher's point of view, sensations coming from the memory for tagging are as real of a sensation as any other sensation coming through the doors of perception.

Other story:

I was eating ice-cream the other day and when I ate all in my cup I got some more from the freezer and ate that too. It's like a normal everyday story. But after having eaten the second portion, I realised that the craving after eating the first one was exactly the same as the craving after the second one. I realised that cravings cannot be satisefied by feeding them, they can only be postponed but you will have to deal with them in the end. I don't know if it was an insight, but it looked like one at that moment.

I remember this teaching from this enlightened master called Osho. He has a lot of his free books online by the way. When a student asked him how to get over his smoking, he answered something like this. "Smoke more deeply, and feel the breath of the smoke in your lungs fully. Be mindful of it." The student looked at him like he was insane, but when he came back, he got over his smoking habit. Why? We crave food because we are not willing to be fully aware of our cravings. We want to run away from them because we don't want to fully admit to ourselves that we have this craving, but only by being aware of it, that you can actually control it. 

Check out mindful eating if you haven't already if you're curious.

I haven't heard of it yet but I'll take a look thanks. As for cravings, I gave up smoking after new year's eve. The cravings were quite strong but faded away quickly. They come back every now and then but most of the time they just come and go, I almost never extrapolate on them.