FORT WORTH — TCU’s PepsiCo Hall filled to near capacity Sunday afternoon for the valedictory performance in the 2013 Mimir Chamber Music Festival.Artistic Director Curt Thompson and pianist John Novacek opened with Igor Stravinsky’s Duo Concertante for violin and piano, a work that brims with melodies.As in earlier concerts, Novacek overpowered from time to time.However, they gave a charming performance, underlining the romantic leanings of Stravinsky’s score. They filled the gigue in the fourth movement with the joyful spirit of kids skipping home from school.Many summers of playing together have given the four accomplished string players who finished the program — violinist Frank Huang (Houston Symphony concertmaster); violinist Jun Iwasaki (Nashville Symphony concertmaster); violist Kirsten Docter (Namburg String Quartet); and cellist Brant Taylor (Chicago Symphony) — the polish of an established quartet.An extra rehearsal may have helped them gel more, musically, for this performance. They took on two difficult, weighty pieces. Both Benjamin Britten’s haunting String Quartet No. 3 and Antonín Dvorák’s somewhat cheerier String Quartet in C Major, Opus 61, lacked an overarching sense of architecture — where the music was going — required to carry the listener along. As a result, both pieces felt long and repetitive.On the plus side, the intonation variances in earlier concerts were resolved.Huang and Iwasaki impressed as they traded virtuoso passages in the Dvorák, along with Taylor’s sonorous cello and Docter’s forthright viola work.The Dvorák, while not an ideal festival-ender, had enough bravura to bring the audience to its feet.