From The Making of Eastern Europe: From Prehistory to Postcommunism, by Philip Longworth (Lume Books, 2020), Kindle pp. 157-158:
Between 1860 and 1900 the population of Eastern Europe almost doubled. Between 1900 and 1914 it increased by at least another 20 per cent to a figure well in excess of 250 million. This was a far higher growth rate than in any Western country, and it has never been adequately explained. In so far as the statistics exclude migration abroad, the situation was worse than it might seem. Mass emigration had gathered pace since 1880. By 1914 nearly 4 million had left Austria-Hungary; the rate of migration from the Russian Empire approached 100,000 a year. But the migration rates from the poorest areas were the lowest (higher for Austria-Hungary than Russia, higher from Russian Poland than the rest of the Russian Empire, and lowest from Romania). However encouraging a development the population explosion might seem to chauvinistic nationalists, it brought rising despair in the countryside (where almost 60 per cent of Austria’s subjects lived, 70 per cent of Hungary’s and over 80 per cent over the remainder of the region). The despair at having to feed more mouths from the same small trough turned to anger in massive peasant disturbances in Russia in 1905–6 and a bloody Romanian uprising of 1907. But the problems of the countryside were also transferred to the cities.
The population growth in most of the major cities exceeded that for the region as a whole because of urban migration. Between 1880 and 1910 the population of Prague rose by almost 40 per cent to nearly a quarter of a million; that of Budapest doubled to reach almost 900,000; those of St Petersburg and Moscow more than doubled (to 2 and 1.5 million respectively), and that of Warsaw more than tripled (to 856,000). But the most alarming increase occurred in Vienna which changed, within the span of a single generation, from a pleasant, orderly, German-speaking city of fewer than 750,000 souls to a polyglot maelstrom of over two million. The city, whose ancient walls had recently been dismantled to make way for the elegant Ringstrasse with its modern palaces and pleasant parks where bands played Strauss waltzes, was suddenly overwhelmed by a new kind of invasion.
It was an irony of this age of nationalism that by 1910 no less than 8 per cent of all Czechs should reside in Vienna (5 per cent of all Slovaks had settled in Budapest by that time). And not only Czechs, but Serbs, Romanians, Slovenes and Ukrainians had flooded in to the new tenements and slums. The city had come to resemble a Tower of Babel, and the indigenous Viennese felt overwhelmed; their culture, their very identity seemed threatened. The popular mood, formerly easy-going, became ugly.