Consider precomputing Element#tagName.

[zmike]

According to jgraham:

It looks like someone didn't finish the namespace implementation for elements
At the moment they store something called tag_name
But they should store local_name and tag_name should be computed

[bzbarsky]

Computing tag_name is slow, actually. We want to be storing both, probably in something like Gecko's shared nodeinfo structs.

[jdm]

#854 is relevant, in that case.

[jdm]

Pretty sure Node.name and Node.local_name cover this.

[jdm]

I can't read. We now store Element.local_name and compute the tag name.

[mbrubeck]

If this is still something we want to fix, it would involve taking the logic from Element::TagName and performing it when the element is created (for example in Element::new_inherited_with_state) and storing the result in a new field of the Element struct. Then TagName could just return the value of that field.

[Ms2ger]

Note that the computed value needs to be updated if the owner document changes.

[bzbarsky]

Right.

I really do think the way Gecko does this (with a shared nodeinfo struct) is pretty good, I don't know to what extent the sharing would be a problem for Servo...