Please help, learning NIM to speed up Python programs, but strange results

[epoz]

Dear Nim community,

I am investigating porting some of the speed critical parts of my projects to 
Nim from Python, for performance reasons. Doing some naive initial tests, the 
Nim was significantly slower, so I must be doing something wrong. Here is the 
Nim:
    
    
    import zip/gzipfiles
    import times
    
    echo now()
    let filePath = "somelargefile.nt.gz"
    let file = newGzFileStream(filePath)
    var count = 0
    
    let startTime = cpuTime()
    while not file.atEnd:
        var l = file.readLine()
        count = count + 1
        if count mod 1000000 == 0:
            let lps = int(count / int(cpuTime() - startTime))
            echo now(), " ", count, " ", lps
    
    echo cpuTime() - startTime, count
    file.close()
    
    
    Run

and here is the Python:
    
    
    import time, gzip
    
    start_time = time.time()
    count = 0
    line = True
    with gzip.open('somelargefile.nt.gz') as F:
        while line:
            line = F.readline()
            count += 1
            if count % 1000000 == 0:
                lps = int(count / int(time.time() - start_time))
                print(time.ctime(), count, lps)
    end_time = time.time()
    print(int(end_time - start_time), count)
    
    
    Run

Any tips on what I am doing wrong?