Altering a resume for a job will indeed take more time than just sending the master copy across to all companies but once you take the effort to tailor your resume to the job description, it will also increase your chances of landing your dream job. When your resume finally crosses the automated screening and reaches the hiring manager, they are sure to notice the critical points that you would have highlighted.
Hiring managers appreciate the additional effort. It shows your patience, commitment and eye for detail and these skills would be a plus in any team. You have not only put in the hard work to go through the job description, but you have also taken out time to look at your own skills and match it to your dream job. This is like preparing for the interview.
The thing about resumes is that while a master resume may not get you as many hits or calls as you like, a tailored resume will change that. It might seem like a lot of work but once you see the result, you will not want to go back to the old method of sending the same resume to all job postings.