There are many techniques available today for publishing maps in web browsers. The material is often created using geographical information systems (GIS). The performance, most often understood as the speed of loading the application into a web browser, is the determinant of the viewing experience. The performance of a map application can be improved through such process as minification. The purpose of the study is to measure the impact of minification on the performance of the map component. Code minification was performed by selected web applications. The performance of two applications, GTmetrix and Dareboost, was tested. Two research questions have been posed: RQ1: How great a reduction in the size of component files of an application can be achieved with minification? and RQ2: How will the minification affect the performance of a web browser map application? The research has shown that the model applications were performing relatively poor, in particular, on mobile devices. The minification reduced the size of HTML, CSS, and JavaScript files by about 11%, which had a slight impact on application performance (in the employed research design). It has been demonstrated that minification was insufficient for improving significantly the performance of the tested applications. Additional compression of image files is recommended.