The analysis of performances constitutes an important stage of a study of sector. The detection of factual difficulties of sectors of activities is a precondition in the analysis of strategies of adaptation which constitute the reactions of firms to performances. We propose in the present study a methodology combined by two indirect criteria of detection of sectorial difficulties. The first is based on the gap of sector’s growth in comparison with activity as a whole. The second criterion imposes an additional constraint on the sector’s growth by deducting a second gap of performance in comparison with the performance of the GDP in relation to its medium autorealization over long period. The detection of sectors in trouble leads us to estimate the weight in the GDP coming from sectors "in trouble" but also from relatively competitive sectors. Our study applied to the case of Tunisian economy highlights some less competitive sectors than activity as a whole. It emerges from it that about 40 % of the GDP on average over the period 2001-2014 results from sectors judged in trouble. To remain optimistic, we suppose that this rate represents a significant potential of catching up for the economic growth.