(in|into) high gear

in a state that is extremely efficient or active

The phrase "in high gear" is believed to have originated in the early 20th century, and it is a reference to the highest gear in a manual transmission vehicle, which allows for the fastest and most efficient speed. This idiom is used to describe a situation where someone is operating at their highest level of productivity or efficiency.

After months of planning, the marketing campaign finally went into high gear with the launch of the new product.
She's been in high gear all week, finishing her projects ahead of schedule and taking on new tasks.
The athletes were in high gear during the final stretch of the race, pushing themselves to the limit to cross the finish line.
The company has been in high gear since the launch of their new product, with sales and production at an all-time high.
When the pandemic hit, the hospital went into high gear to prepare for an influx of patients.