Thomas Sutcliffe: You have to cut it out to pack 'em in

Glancing at the publicity details for David Cronenberg's Eastern Promises I saw one fact that immediately appealed. It was only 100 minutes long. Not edifying, I know, but I'm afraid that weighing up a creative product in this way is one of the occupational hazards of professional arts consumption, like miner's lung or white finger. You want to know what sort of temporal investment is going to be required of you, so you ask "How long is it?" – and the answer, whether it comes as a curtain time or a pagination, invariably starts to colour your responses.

As it happens, I would suggest that film critics are less prone to this tendency than some of their colleagues, but even for them an extensive running time can induce a premonitory depression that only the very best film is likely to lift. I remember a screening of David Lynch's three-hour long Inland Empire at which the general mood before the lights went down suggested that everybody present was bracing themselves for a colonoscopy.

In the case of Cronenberg that relatively tight running time was reassuring for two reasons. Firstly, it suggested that his thriller would consistently thrill – not sag at the centre into something pretentiously metaphysical (being unpretentiously metaphysical takes much less time). And secondly, it showed that there are still directors fighting the general trend towards greater length, a tendency that seems to have affected every genre of film, however impatient and fidgety their target audience.

A couple of weeks ago I sat through Ratatouille – Pixar's latest computer animation – and felt as if it would go on for ever. At 110 minutes it isn't actually hugely long by current standards, but The Jungle Book was over half an hour shorter, and seemed to get far more on screen. Pixar should know better – Toy Story was just 81 minutes long and, I would guess, will last a lot longer than Ratatouille.

It's hardly news that films are getting longer, of course. People started complaining about it in the Seventies and Eighties, when power shifted from producers to directors, and the curb and bit fell into disuse. The average running time for the 10 films shortlisted for Best Picture in the 1937 Academy Awards was 117 minutes (artificially inflated by Anthony Adverse and The Great Ziegfeld, both of which unusually broke the two-hour barrier). In 1978 the average running time of Best Picture Nominees was 130.8 minutes and in 2006 it was 137.2 – helped upwards by the 170-minute running time of Scorsese's The Aviator. The average dropped back a little last year, but the general trend is still broadly upwards. And I doubt there is a cinema-goer that hasn't felt the effect at some time or other, as you encounter one of those passages where it suddenly becomes apparent that the director's passion for his or her work conspicuously exceeds ours.

It's philistine to pine for brevity, of course. Cinema exhibitors much prefer short films because they can turn the showings faster and rack up better foyer sales (look at the prices the next time you visit a multiplex and you will see that it's actually an outlet for overpriced snacks with some screening rooms attached). Producers prefer them for much the same reason, because the box office return is at heart what it's all about. Against these pragmatic butchers the director and writer is always perceived to be on the side of art. But a lot of the received opinion about the combat between the cutters and defenders dates from a time when films genuinely were down to the bone already. Three minutes out of a film that runs 90 may be a much tougher cut than 20 minutes out of one that runs for 150. What's more, cutting is rarely a matter of mere subtraction. You can add to a film's impact by removing the stuff that muffles it.

I would suggest, anyway, that in the history of cinema the number of films that have been spoilt by being too long vastly exceeds those spoilt by being viciously over-pruned. Granted, this is the way perception would tilt things anyway, since we're forced to endure excess fat while remaining blithely unknowing about the saving graces that litter the cutting room floor. But talent will always find a way round tight discipline (think of the rattling pace of the dialogue in a Howard Hawks movie – squeezing two pages of talk into one of screen time). A general liberty, by contrast, is likely to release far more mediocrity than it does trammelled genius, with mediocrity sadly more liable to spread itself widely. I haven't seen Eastern Promises yet, but I feel confident it will conduct its business with a winning dispatch.