After disheartening financial results and the continuing malaise in the industry, Cap Gemini Sogeti SA has decided to reduce its staff for the first time in its history. The 10% cut, approximately 600 people, will come entirely at its French subsidiary, Cap Sesa, which has maintained a policy of full employment for the last two years. This decision is painful but urgent, says Xavier Stefani, Cap Gemini’s personnel director. A meeting of the company’s management-worker council is set for next week to define a plan to help put the people concerned in the best possible condition to find new professional activity quickly. Cap Gemini is only one of many French software and systems integration houses affected by the slowing of growth in the French software and computer services market to 10% in 1991 from 16% in 1990. The growth rate will not exceed 9% this year, according to French market research company Pierre Audoin Conseil SA.