Questions about memory leak JS (try/catch, images in b64, ajax, unset variable, removeChild)

OK, i have a list with a few things that makes think that is the reason why my add-on is using a lot of memory.

1 - Use try/catch can increase memory usage? Example:

try{
  if(!condition) throw "Message";
  //some code
}catch(ex){}

If this is the problem,I was thinking in use:

(function(){
     if(!condition) return;
})();

2 - Use images with base64 can improve memory usage too?

<img src="data:image/png;base64,[...]==" />

Or there is no problem?

3 - I use a function to handle ajax result, so i can use responseXML...

if (o.readyState != 4) return;

var newdoc = document.implementation.createDocument(nul开发者_开发问答l, null, null);

var newhtml = document.createElement('div');

newhtml.innerHTML = o.responseText.replace(/script/ig, "");

newdoc.appendChild(newhtml);

newdoc.getElementById('...');

I cannot use jquery, this is the easiest way that I found to use responseXML, but may causing memory leak too.

4 - Unset variables, helps in something or is unhelpful?

var a = "something";
if(a=="something")
    //

//I'm not going to use the variable "a" anymore, so..
a = undefined; //Now i unset the variable

5 - If you add an Event to a element, or you use appenChild, this increases memory.

element.appendChild(newelement);

If you change the page, looks like the memory is still the same.. If I use

window.addEventListener("unload", function() {
    element.removeChild(newelement)
}

This helps in something too?

Thanks.

Sorry for the english.

On 4 and 5th.

Browser realy increases memory on every additional event\element, but don't decreases it immedialtely after some events\elements got deleted.

In garbage collecting every browser has it's "Dao":) :

• IE 6-8 don't clear memory at all (until you close it or press F5).

• Chrome takes up to 5 minutes to run garbage collector or when garbage size reaches some fixed amount.

• Opera "eats" more memory then any other browser, but frees it immediately after it's became unneeded.

• The fastest is FF nearly 1 minute to clear memory from unused data.