It's simply a case of 'supply and demand'. The more popular a journal is, the more manuscripts it receives to review, the more 'back copy' it has in reserve and, therefore, the less pressure there is for a fast turnaround
Or sometimes just the 'business' or 'motivation' of a reviewer. The business I can understand. The motivation I can't always understand. For instance, recently I had a reviewer who took 3 months to feedback on the manuscript of a Masters student of mine in a good quality journal. It simply said 'I'm not interested in this article'. Personally, I usually respond within a few weeks of accepting to review a manuscript ( and I review for over 30 international journals) and I offer detailed feedback - whether I accept or not. For me - some 'bad apple' reviewers really do hold up the process.
The reviwers of these reputed journal's are very buzy and are all Stalwart with towering research activities in their own field. All are almost heavily engaged in their own work and very few reveiwers are truely professionals, so as to reply in stipulated time span. This makes a overall delayed in the publications and all such things
That's true enough Devang - reviewers are generally advised to offer constructive criticism. The 'natural' nature of many reviewers, however, is to stress the nagative and sometimes skirt over the positives. That can be rather disconcerting for some - especially novice authors
The availability of reviewer is required at the later stage. But we (I and my wife) has been received response after 5 month or some time one year that paper is not matched with our journal. while area matching is the first stage of each manuscript. it represents the laziness of the editor of journals. I think it is just wastage of time nothing else.
Editor must give the some time limit to reviewer for review. If in this time reviewer is not able to review the paper without any time extension request then his/her reviewer ship should be cancel.