The double world champion, who turned 31 on Sunday, actually managed to extend his points lead to a margin of 40 at the Hungarian Grand Prix.
That was despite the Ferrari driver finishing back in fifth place, 25 seconds off the pace of the winning McLaren of Lewis Hamilton.
Alonso would have finished even lower had strategy errors from McLaren and Red Bull respectively not dropped Jenson Button and Mark Webber behind him.
The result ended a strong sequence for Alonso, who had won two of the previous three races and finished second in the other, with the Spaniard's inspired form this season leading many to believe he is at the peak of his powers.
But such was his disappointment at Ferrari's lack of pace, he knows that his title hopes may start to fade if there is not a marked improvement when F1 returns from its month-long summer break at the start of September in Belgium.
He said: "We have a lead of 40 points, courtesy of a car that has not been the best in this first half of the season.
"Now we must try and make a good leap forward in terms of performance to allow us to keep the lead in the championship, because in the long term, what we have now will not be enough.
"If we are where we are, it's because we have always made the most of what we had and because of an excellent reliability record: it's not by chance that you get 23 consecutive points finishes.
"July has been a tough and stressful month, with three races and a lot of work at the factory.
"Now I want to take a break for a bit and fully recharge the batteries, to show up again in Spa in perfect shape, in the hope that the second part of the season is as positive and productive as the first."
Webber is currently Alonso's closest challenger in the championship, although the likes of Sebastian Vettel, Hamilton and Kimi Raikkonen are all in close pursuit.
But Alonso believes it is reigning champion Vettel and Hamilton who pose the greatest threat over the course of the remaining nine races.
"We knew this would be a complicated weekend because we were not quick enough, but despite everything, we managed to extend our lead over Webber," he said.
"In terms of the championship it has therefore been a very good weekend. To have finished ahead of one Red Bull and right behind the other in these circumstances was very important because, on paper, we should have expected to finish seventh.
"Hamilton was out of our reach this weekend, but we did not lose much ground to Vettel and these are, in my opinion, the strongest of the group that's behind me in the championship."