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.
Since Meteor automatically scopes by file, you can write your template helpers and event handlers in the same file, and place a reactive data structure at the top of the file that both can access.
You could use reactive-object (my package), as it provides a fairly drop-in reactive object that supports arrays as reactive properties, including all the Array.prototype methods.
Don't make Meteor sound like a toy, though, 'full stack' engineers worth their salt can do awesome things with it if they understand its inherent limitations. I ran Meteor with Redis before their official Redis implementation came out, and I used Redis pub/sub to sync in real-time between 8 different instances of Meteor in production. It rocked.
Just because a framework comes out supporting only MongoDB doesn't mean you have to use MongoDB for everything. It's still on Node.js, and it still supports NPM packages, with some small caveats.
Yes, right now there is a PHP example implementation that should work on most shared hosting as well. No need to open terminal, much less have root access.
I was just discussing this with a friend last night. There is a lot more to going global (or even targeting a new culture domestically) than simply translating your website and/or getting prepared for international shipping (if your product is physical). UX needs to be culturally savvy; ideally, the product/service would be adapted specifically for each culture. If that's out of the budget, a company should at least make sure that they aren't being unintentionally offensive.
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.