Ferrari brought a new floor to Suzuka in September in a bid to improve its aerodynamic efficiency.
The revamp featured changes to the front floor fences, floor edge, mid floor and diffuser sidewall, which worked in unison with a revised sidepod undercut.
The Scuderia's efforts to reduce drag also allowed Leclerc to be more comfortable in the SF-23, after team-mate Carlos Sainz had taken over from the Monegasque as the team's lead driver after the summer break.
While the update itself wasn't worth a huge amount of lap time, it allowed Leclerc to lean on the car harder, which saw him regain the upper hand on Sainz with three podiums and three pole positions across the final five race weekends.
"We had a small upgrade in Japan and I don’t know in terms of pure performance if it was something bigger, but I think in terms of comfort it was important and very beneficial for Charles," Vasseur said.
"I think Charles was in a much better shape in the last part of the season, the last six or seven races. This was a positive dynamic.
Source: Autosport