Speed matters when it comes to landing pages. 53% of visits are abandoned if a mobile site takes more than three seconds to load. With parallel tracking, users will head immediately to your landing page after clicking your ad while their browser processes click measurement requests in the background.
Last year, we announced that parallel tracking would be expanded to Display and Video campaigns in March 2019. Parallel tracking for Display and Video campaigns will now be available starting May 1st, 2019. Therefore, advertisers now have more time to prepare before parallel tracking becomes mandatory for all Display and Video campaigns starting July 31st, 2019.
If you need to make ad URL changes, your ads will need to be reviewed. So reach out to your click measurement provider as soon as possible. If you have Display and Video campaigns across multiple accounts, we recommend spacing your changes over multiple days.
Source:
Google