Faster Filter Take 9,000

filter.fs

let filter f (array: 'T[]) = 
        
    checkNonNull array
                
    if sizeof<'T> < 4 then        
        let tmp = Array.zeroCreate array.Length 
        let mutable count = 0
        for i = 0 to array.Length - 1 do 
            let x = array.[i] 
            if f x then 
                tmp.[count] <- x
                count <- count + 1
        Array.sub tmp 0 count
    else                
        let temp = Array.zeroCreate array.Length
        let mutable count = 0
        for i = 0 to array.Length-1 do                
            if f array.[i] then
                temp.[i] <- true
                count <- count + 1
                    
        let res = Array.zeroCreate count
        count <- 0    
        let mutable i = 0
        while count < res.Length do
            if temp.[i] then
                res.[count] <- array.[i]
                count <- count + 1
            i <- i + 1
        res