Hello Alex,
Our webhooks can't be selected, it is either all or none.
The only thing you could do is try and drop any webhook whose post body doesn't contain 'type':'deal', but this won't solve the issue of a lot of requests reaching your server.
An alternative to webhooks has always been polling for changes. You can make regular requests to our API to check for deals which have been edited since your last request. This could be a great solution if your own system doesn't have to be instantly synced with OnePageCRM. A rate of checking once every 30seconds - 5 minutes would probably be sufficient then and would bring far less load to both of our systems.
The only place where this approach may fall down is if and instantaneous sync is needed, in case your users regularly win a deal and then immediately use you own system to work with the deal there.
We haven't received many requests for this feature, so I can't say it will be implemented anytime soon. But I've added it to our public Trello road map as an idea. If you comment there, it may become a reality sooner rather than later 
