diff --git a/src/imgtests/runner.py b/src/imgtests/runner.py
index 794fd4f2..7e6b0893 100644
--- a/src/imgtests/runner.py
+++ b/src/imgtests/runner.py
@@ -597,6 +597,11 @@ def _run_single(distro: Distro, mode: Runner, config: dict[str, Any]) -> None:
 
                     if filtered_tests:
                         suite.tests = tuple(filtered_tests)
+                        suite.test_duration = (
+                            suite.total_duration // len(filtered_tests)
+                            if len(filtered_tests) > 0
+                            else suite.test_duration
+                        )
                         logger.info(
                             "Filtered %s: %d -> %d tests",
                             suite_name,
diff --git a/src/imgtests/web/static/js/test_config.js b/src/imgtests/web/static/js/test_config.js
index 79dd4971..c5cfcf25 100644
--- a/src/imgtests/web/static/js/test_config.js
+++ b/src/imgtests/web/static/js/test_config.js
@@ -333,26 +333,30 @@ class TestConfigManager {
                         ),
                     ).map((cb) => cb.value);
 
-                    if (!this.currentConfig.selected_tests) {
-                        this.currentConfig.selected_tests = {};
-                    }
+                    const selectedTests = {
+                        ...(this.currentConfig.selected_tests ?? {}),
+                    };
 
                     if (selected.length > 0) {
-                        this.currentConfig.selected_tests[suiteName] = selected;
+                        selectedTests[suiteName] = selected;
                         this.showStatus(
                             `Selected ${selected.length} tests for ${suiteName}`,
                             "success",
                         );
                     } else {
-                        delete this.currentConfig.selected_tests[suiteName];
+                        delete selectedTests[suiteName];
                         this.showStatus(
                             `Will run all tests for ${suiteName}`,
                             "success",
                         );
                     }
 
+                    this.currentConfig = {
+                        ...this.currentConfig,
+                        selected_tests: selectedTests,
+                    };
+
                     modal.remove();
-                    this.renderConfigUI();
                 });
 
             document
@@ -424,6 +428,7 @@ class TestConfigManager {
                 const error = await response.text();
                 throw new Error(`HTTP ${response.status}: ${error}`);
             }
+            this.renderConfigUI();
         } catch (error) {
             console.error("Save failed:", error);
             this.showStatus(