Sandra Bullock Says Keanu Reeves Is So Zen, He Replies a Day Later

Sandra Bullock says Keanu Reeves is so calm and measured, he sometimes takes a full day just to respond to her ... which is pretty much the exact opposite of how she operates.

Sandra opened up about their longtime friendship on Amy Poehler's "Good Hang" podcast ... explaining she and Keanu clicked despite being wildly different personalities.

She described Keanu as "very reserved and Zen," while she's more likely to fill the silence ... joking she's basically a "whirling dervish" around him until she wears herself out.

And Keanu apparently isn't big on instant reactions either.

Sandra says he'll sometimes hear her out and then wait until the next day to respond ... after he's had time to really think about what she said.

She admitted it's something she could probably learn from, with Amy comparing the pair to "the tortoise and the hare."

As TMZ previously reported, Sandra and Keanu have stayed close long after starring together in "Speed" and "The Lake House" ... even reuniting for a 30th anniversary screening of "Speed" in 2024.