The COVID-19 pandemic is a substantial challenge for national economies. The survivability and better performance of some companies can serve as lessons for others, and those who learn the said lessons faster will take the lead in the post-COVID world. One of the national economic development drivers is high-growth firms (HGFs), also known as gazelles. High-growth middle-sized firms (HGMFs) have a notable impact on the national economy as significant employers, producers, and tax-payers. This paper aims to find the peculiarities in the reactions of HGMFs to the COVID-19 pandemic based on Russian firms’ data. This research uses the official statistics of middle-sized Russian firms (7944 firms, 238 gazelles). Gazelles are identified based on 2016–2019 data and then compared with normal medium-sized firms (NMFs) using 2020 data. In total, 14 hypotheses are formulated and tested, with those hypotheses focused on five aspects of firms’ performance: the ability to grow, profitability, efficiency, solvency, and employability. The research utilizes a one-way ANOVA test and Z-test for proportions for different types of hypotheses. Hypotheses testing shows that HGFs demonstrate better ability to grow, better efficiency, better solvency, and better employability than normal firms. However, they cannot maintain their higher profitability in 2020, despite higher net income values in comparison with other companies. The research confirms that HGMFs have unique capabilities to overcome these kinds of crises, and that such capabilities can be scaled to other business entities to increase their survivability in times of future crises. The research can be extended to small firms, 2021-year data analysis, and comparative cross-industry or cross-country analysis.