Real Madrid and Girona cannot be compared because the difference in quality between these two teams is very different, but Girona this season has the confidence and chemistry of the players which is quite close so that they can produce good performances throughout this season.
Until now I have not seen any difference or decline in Girona's performance.
Girona and Barcelona's competition for 2nd place in the standings may be a bit fierce because Barcelona has not had consistency throughout this season so even if Girona gets some bad results they still have a chance to still compete for 2nd place.
These two clubs are very different in that Real Madrid has been the only most successful club in La Liga and the world for a long time while Girona has only performed slightly better this season. But even so, they lost their balance and in the end gave up the top position of the standings to Real Madrid because they experienced consecutive defeats in several previous matches. Girona's performance has actually decreased compared to the start of the season until several matches made them top of the standings.
They lost twice to Real Madrid at home and away and most recently also suffered defeat against Athletic Club and several draws made their position drop to second place. If calculated overall, Girona's performance has not declined much, but they are competing with clubs that are much stronger so mistakes could put them at a disadvantage.