Bruno Ecuele Manga's first goal for nearly 12 months, a powerful 18th-minute header from a Peter Whittingham corner, gave Cardiff a 1-0 victory and took them three points clear of Ipswich.
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Cardiff remain seventh, one place and one point from the play-off positions, but are on a roll having won four of their last six games.
"It was a big win for us," said Slade.
"I'm not a great believer in six-pointers because you can never do that, but the three points are huge for us as it's about the results at this time.
"Ipswich are probably the best at grinding out a result in this league and we have done it to them.
"I'm proud we've done that, that we've been ugly. It was not pretty, we were fighting."
Slade has come in for much criticism from Cardiff fans since his appointment in October 2014.
The former Leyton Orient and Brighton boss has been criticised for Cardiff's style of play and the team's failure to get into the play-off positions.
But there are signs that Slade is slowly winning some of the fans over and he made a point of celebrating with them at the final whistle.
"I'm delighted if the fans are behind me, it's fantastic," said Slade.
"Since I've been here, it's been a question of trying to win fans over and just work hard.
"We've done that. We've got a unity in the dressing room and the fans have responded to that.
"I do appreciate that, I know how keen they are to be in the top six and in the shake-up to get back to the Premier League again.
"It's been a test of character and our desire in what has, at times, been a difficult season.
"We've nine games left and we have an opportunity still."
Ipswich manager Mick McCarthy did not hide his displeasure after losing vital ground in the play-off race.
"I feel frustration because there's nothing in the game except for one corner kick," said McCarthy.
"It's a great cross and great header for the goal, but he (Manga) should not get a free header in our box.
"We've not done enough to win it, but we should have defended better and got a 0-0 draw.
"I was settling for a horrible, turgid game and I thought we might nick it from a corner, but it's ended up the other way."
Ipswich have fallen four points off the play-off pace after winning only twice in seven games.
But home games against Blackburn and Rotherham this week offer them the opportunity to put pressure on the top six.
"We've got two home games and we really need to win them to get back in the mix," said McCarthy.
"But there are no mugs in this league and they will be difficult games."