Golang，csv.writer。将20k行写入CSV将冻结我的PC

I have an issue on Linux Ubuntu with 1.4.2, which I am not sure how to sort:

func main() {
        dir, _ := filepath.Abs(filepath.Dir(os.Args[0]))
        outputFile, outputError := os.OpenFile(dir+"/out1.csv",
                os.O_WRONLY|os.O_CREATE, 0666)
        if outputError != nil {
                fmt.Printf("An error occurred with file creation
")
                return
        }
        defer outputFile.Close()
        writer := csv.NewWriter(outputFile)
        results := getResults()
        for _, result := range results {
                writer.Write([]string{result.Item, result.Price, result.Shipping})
        }
        writer.Flush()
}

when results is 1000+ records my PC freezes for seconds and when it's say 20k, it freezes for minutes. How do I solve such an issue in a proper way? I though to flush it every N records, and add time.Sleep – but that looks awkward…