A surge in app downloads during the Christmas period came at the expense of rising mobile app marketing costs, according to marketing platform company Fiksu.

The Fiksu Cost per Loyal User Index increased by 21 percent in December to hit $1.67 compared to $1.38 in November.

Downloads rose during the period as consumers received tablets and smartphones as gifts, with the Fiksu App Store Competitive Index – the average aggregate daily downloads volume from the top 200 free US iPhone apps – hitting 5.32 million in December, a 16 percent increase compared to a month earlier.

Despite the increased cost per user, Fiksu found that there was a steadier, more cost effective landscape compared to 2011, as best practices learned and tested during the year were implemented.

Competition during December did not increase as much as it did in 2011, which Fiksu attributed to an absence of the robotic install tactics previously used.

“Unlike the spending frenzy we saw in 2011, many opted for a value-versus-volume approach in 2012, collectively applying a more conservative, sophisticated strategy to their Q4 campaigns and largely avoiding big gambles on a long App Store freeze,” said Micah Adler, Fiksu CEO.

“As a result, marketing dollars were spread to the long tail of apps outside the top 200, and the peaks in volume and cost per loyal user, while still significant, weren’t as extreme as they were in 2011,” he added.