"They were very, very opaque about what the changes are, and the impact of the changes," he said, but added of Alphabet's revenue growth: "It is showing potential signs of strain."
A year ago, a 25 per cent jump in revenues coincided with an acceleration of growth at the big consumer internet companies to set the stage for a strong share price rally in the sector.
The rise in the US dollar was a significant factor in the slowdown since then, said Ruth Porat, chief financial officer — currency fluctuations had added 3 percentage points to growth in the first three months of 2018 but wiped 2 points from growth this year.
She also warned that "the timing of product changes can impact year-on-year growth rates" — a standard caution from Google executives, but a more pointed one this time round.
Changes to advertising on YouTube contributed to a big jump in the number of times internet users clicked on Google's adverts in the first three months of last year, leaping by 59 per cent. By contrast, with no new changes with an equally powerful effect, the growth rate in clicks fell to 39 per cent in the latest quarter.
Sundar Pichai, chief executive, said the company did not manage the timing of new services around its quarterly earnings calendar. "We have a long-term view of where we want to go. You are going to have quarter-to-quarter variations once in a while," he said.
While its revenue performance disappointed investors, Alphabet turned in stronger earnings than analysts had forecast in the first quarter — the opposite of what investors have come to expect from the company, which has been investing heavily for growth in recent quarters.
Alphabet's earnings for the period fell by 29 per cent, to US$9.50, as it took a US$1.7b charge to cover the cost of a fine by the EU in March, over what regulators claimed were anti-competitive restrictions it put on advertisers.
Without this, it would have reported earnings per share of US$11.90, or more than the US$10.58 that analysts had been expecting. The figures benefited from lower traffic acquisition costs at Google, or the money the company pays out to partners that carry its ads, as well as lower than expected marketing spending.
Alphabet's overall capital spending also fell 40 per cent, to US$4.5b, after hitting US$25.1b for all of last year.
However, Porat indicated that Google was not planning to let up on its heavy investments this year. Capital spending was expected to grow from the heady 2018 level, though at a much slower pace. The company has earmarked US$13b alone in the US this year for investment in new data centres and office expansion.