mat-select seems to have serious performance issue

#### Bug, feature request, or proposal:
With latest release, mat-form-field support was added for mat-select. But it introduced performance issues when we have multiple select lists (5-8).

When we use mat-form-field with input or text area it doesn't seem to cause any performance issue but it seem that its implementation for mat-select needs a review. On lengthy forms we are seeing a delay of up to 3 seconds, which are instant without mat-form-field on mat-select.

#### What is the expected behavior?
It should smooth and fast.

#### What is the current behavior?
Its very slow.

#### Which versions of Angular, Material, OS, TypeScript, browsers are affected?
Angular 4.4.4
Material 2.0.0-beta.12
Chrome

Le rapport mentionne mat-select et mat-form-field, mais aucun fichier, test ou point d’entrée pour la reproduction. Commencez par reproduire le délai signalé avec 5–8 contrôles mat-select sous Angular 4.4.4 et Material 2.0.0-beta.12, puis comparez-le avec mat-select sans mat-form-field. Le travail est terminé lorsque le formulaire volumineux n’affiche plus le délai de plusieurs secondes signalé et que le comportement est couvert par un test de régression ou un benchmark.

Rédigé par le modèle d'indexation à partir du texte de l'issue.