The bottleneck with the reviewing of papers is actually the reviewers. To find peer reviewers, the editor has to read the paper and decide and find, which peers are suitably qualified to do the review.
The potential reviewers are contacted on individual basis and asked if they would review the paper. Once enough reviewers has reviewed the work, their reports are collated by the editor and the feedback becomes available. Generally, the more specialized the topic is, the harder it gets to find suitable (and willing) reviewers.
In the light of this tedous and manual process, 3 months does not seem bad.
Because, basically, reviewing a paper is a voluntary work. So most people do not consider paper review as highest priority, and often forget about it until a reminder mail has been received from the editor (which is normally after due).
it is just as people say above, I know it from both sides, having organized several journal special issues, for example: First of all, the paper is submitted. This does not mean it is immediately on your desk. It may arrive at an editorial office that distributes papers to a suitable associate editor, whose task it is to select and invite reviewers. Now you have the paper. You have to have a look at it and decide upon suitable reviewers. You invite the reviewers for the paper. They get time to respond, say, two weeks. You can't invite five at the same time, because that way, if all accept (though not all do, usually), you may have to uninvite some. So you wait for the two to respond. If you are lucky, you have an editorial system at hand that allows you to name alternative reviewers that are automatically promoted & invited once your initially invited reviewers decline. If not, besides your main work, you wait for the response. Often you have to remind people to respond, so they get another deadine. More than a month has passed by now and no review was written yet. Finally your reviewers agree. They get another deadline. This varies from journal to journal, but can usually be found out. Sometimes it is two weeks, but I have heard people telling about as much as 3 months, too. Maybe you should check that for the journal in question - it is possible that your manuscript is still absolutely on time. So reviews are starting now, and you are lucky: One reviewer delivers an immediate answer. Fine you think, but then you have a closer look at the review and notice that all the reviewer remarked was the author should cite his (i. e. the reviewer's) own papers - think was this does to the idea of "blind" reviewing. Well, anyway, it means you have a review, but it is worthless. So you start inviting an alternative reviewer ... and the same process as above starts again, and still you don't really have a review at hand ...
I won't go on. Obviously, this is a worst case scenario, but it can happen to anyone. As David Johnson above said, reviewing is a voluntary job, and we should be thankful that some of us take this additional load upon their shoulders. Paying for peer review and having professional reviewers has sometimes been suggested, but I am very doubtful about that (I won't discuss it here, there has been another question on this around already).
So for the moment I think you just have to accept that the process has difficulties that can create incalculable delays.
Best thing you can do, I think, is write a friendly message to the editor, as Harpreet Grewal suggested above.
A review of a resubmission is not necessarily easier: Reviewers may state they would like to do a review of a resubmission, if that applies, but they may also choose not to offer this, so the process is the same as in the case of an original submission.
In what journal - maybe i know ? Usually , a revision deadline is 14-to max.30 days.I think you must contact the Editor in chief of the journal. 3 month without a answer from the editor is too much and is an abusive behaviour of the journal.
I disagree. It is not abusive, because from the editor's side, you sometimes just can't help it. Besides, Elsevier journals, too, leave reviewers time to decide on whether or not they intend to review, Elsevier journals, too, have to wait for reviewers to reply and hope for them to keep to the deadlines, first when answering the invitation, then when actually preparing the review.
Dear Dr.Lehmus, i maintain my opinion - three month after submission the revised paper (without any feedback from the journal !) is too much.We are not in old times when the corespondence with journals was done by mail ( not email :)).
Alright, I am ready to concede feedback from the journal would be a matter of good manners and could easily be done ... and even be generated automatically, which would probably mean a deduction in the politeness grade, though. :-)