Ben Chorley's 51st-minute penalty after Gary Teale's handball opened the scoring and from there Orient ran riot, with Harry Kane netting his first senior goal before late strikes from Alex Revell and substitute Paul-Jose M'Poku.
Slade's side are now unbeaten in 10 matches and he said: "We told the players at half-time just to keep going. Sheffield Wednesday came with a good game plan and they contained us in the first half.
"We told our players to keep their energy levels high. We felt that we just had to keep doing what we did in the opening half and we would get our rewards.
Slade reserved special praise for goalscorers Kane and Revell amid an impressive team display.
"I was delighted for the young lad Harry Kane who did really well for us and got his goal in his first league star. Alex Revell was superb for us, he probably covered every single blade of grass and it was a fantastic performance."
Source: PA
Source: PA