diff --git a/tests/zstreamtest.c b/tests/zstreamtest.c
index 4d32c19e..a7af89eb 100644
--- a/tests/zstreamtest.c
+++ b/tests/zstreamtest.c
@@ -1808,7 +1808,8 @@ static int fuzzerTests_newAPI(U32 seed, U32 nbTests, unsigned startTest,
             }
             {   U64 const pledgedSrcSize = (FUZ_rand(&lseed) & 3) ? ZSTD_CONTENTSIZE_UNKNOWN : maxTestSize;
                 ZSTD_compressionParameters cParams = ZSTD_getCParams(cLevel, pledgedSrcSize, dictSize);
-                static const U32 windowLogMax = 24;
+                const U32 windowLogMax = bigTests ? 24 : 20;
+                const U32 searchLogMax = bigTests ? 15 : 13;
                 if (dictSize)
                     DISPLAYLEVEL(5, "t%u: with dictionary of size : %zu \n", testNb, dictSize);
 
@@ -1818,6 +1819,7 @@ static int fuzzerTests_newAPI(U32 seed, U32 nbTests, unsigned startTest,
                 cParams.hashLog += (FUZ_rand(&lseed) & 3) - 1;
                 cParams.chainLog += (FUZ_rand(&lseed) & 3) - 1;
                 cParams.searchLog += (FUZ_rand(&lseed) & 3) - 1;
+                cParams.searchLog = MIN(searchLogMax, cParams.searchLog);
                 cParams.searchLength += (FUZ_rand(&lseed) & 3) - 1;
                 cParams.targetLength = (U32)((cParams.targetLength + 1 ) * (0.5 + ((double)(FUZ_rand(&lseed) & 127) / 128)));
                 cParams = ZSTD_adjustCParams(cParams, pledgedSrcSize, dictSize);
@@ -1862,8 +1864,9 @@ static int fuzzerTests_newAPI(U32 seed, U32 nbTests, unsigned startTest,
                     CHECK_Z( ZSTD_CCtx_setPledgedSrcSize(zc, pledgedSrcSize) );
                 }
 
-                /* multi-threading parameters */
-                {   U32 const nbThreadsCandidate = (FUZ_rand(&lseed) & 4) + 1;
+                /* multi-threading parameters. Only adjust ocassionally for small tests. */
+                if (bigTests || (FUZ_rand(&lseed) & 0xF) == 0xF) {
+                    U32 const nbThreadsCandidate = (FUZ_rand(&lseed) & 4) + 1;
                     U32 const nbThreadsAdjusted = (windowLogMalus < nbThreadsCandidate) ? nbThreadsCandidate - windowLogMalus : 1;
                     U32 const nbThreads = MIN(nbThreadsAdjusted, nbThreadsMax);
                     DISPLAYLEVEL(5, "t%u: nbThreads : %u \n", testNb, nbThreads);