What is the file size (in Kb or Mb)? Is that number larger than should be needed for the amount of data and formulas you have?
If that's the case, you probably have unneeded infomation being saved with the file.
Sometimes this occurs when data, formulas or formatting is inadvertently copied to all the rows in the worksheet.
If your workbook is fairly simple, you might try starting a new workbook, copying in just the data, formulas and formatting for just the range(s) you are using. Don't copy the entire worksheet or you might just transfer the bloated part.