Having worked with Meteor for 8 months by now, my love affair with it is slowly fading.
I guess I've realized that it's too far on the left on the [framework...library] scale for my liking. It's very "don't call us, we'll call you". Which is awesome when you start because you just sort of put stuff out there, functions, collections etc., and Meteor magically picks it up and does stuff with it. Yes, you can still debug everything and it's all open source so nothing is black boxed, but it's still really annoying when the magic doesn't work or worse, when it works but just not very well. As with one of my apps at the moment, that is suddenly slow. Everything works so there is no error message that I can use as a break point. But it just takes a long time for my update function to be called for whatever reason, and debugging that takes me far into territory that I don't know about and frankly don't care to know about.
Libraries, on the other hand, require you to say more specifically what you want to happen, but then you can either see that it happens or not. And debug that one particular function if it doesn't, or if it's slow.
I have tremendous respect for the work that they are putting in; iteration is really fast and problems are being solved quickly so there is no doubt in my mind that Meteor will become one of the major platforms of the web like Rails did, but it's going to be a while before I will be using it for new projects.
What is nice about meteor is how quickly you can get off the ground and build something with it. Then you realize: I have no idea how this stuff works. Is it secure? When do things update? Is there too much magic?
But if you spend a bit of time learning how meteor’s core packages work (deps, ddp, livedata, blaze, etc) and how they work together — almost all of the apprehension disappears.
I recommend digging into the Deps package first, it powers reactivity and is surprisingly simple (only 1 kb).
Meteor also started putting together a manual to explain the core concepts http://manual.meteor.com — the first chapter is about the Deps package.
With any new concept there is a learning curve. But I believe the concepts meteor introduce are too powerful to ignore. The saying is that any sufficiently advanced technology is indistinguishable from magic :)
I would recommend checking out Kadira for optimizing your app. It's pretty amazing the kind of information you get out of it, and Kadira Academy teaches you a lot about Meteor's internals.
Also, if your app is now "suddenly slow", I'm guessing it's been around for a while. If you don't have the proper indexes on MongoDB it's going to get slower as it loads up with more data. I've experienced this first-hand, migrating a Rails app from Postgres to Meteor/MongoDB. We have millions of records, and one missed or incorrect index can slow the whole app down, sometimes unbearably.
Having not used Meteor (beyond toys) but trying to understand how it works this sounds exactly like what I would expect to hear.
But I hope you are wrong about becoming a major platform for the web, unless it drasticly changes. These Node frameworks keep astounding me in their use of stateful servers and relying on vertical scaling.
I guess I've realized that it's too far on the left on the [framework...library] scale for my liking. It's very "don't call us, we'll call you". Which is awesome when you start because you just sort of put stuff out there, functions, collections etc., and Meteor magically picks it up and does stuff with it. Yes, you can still debug everything and it's all open source so nothing is black boxed, but it's still really annoying when the magic doesn't work or worse, when it works but just not very well. As with one of my apps at the moment, that is suddenly slow. Everything works so there is no error message that I can use as a break point. But it just takes a long time for my update function to be called for whatever reason, and debugging that takes me far into territory that I don't know about and frankly don't care to know about.
Libraries, on the other hand, require you to say more specifically what you want to happen, but then you can either see that it happens or not. And debug that one particular function if it doesn't, or if it's slow.
I have tremendous respect for the work that they are putting in; iteration is really fast and problems are being solved quickly so there is no doubt in my mind that Meteor will become one of the major platforms of the web like Rails did, but it's going to be a while before I will be using it for new projects.