diff --git a/.server-changes/batch-declarative-schedule-cleanup.md b/.server-changes/batch-declarative-schedule-cleanup.md
new file mode 100644
index 00000000000..f13f5e2759c
--- /dev/null
+++ b/.server-changes/batch-declarative-schedule-cleanup.md
@@ -0,0 +1,6 @@
+---
+area: webapp
+type: improvement
+---
+
+Lower background database load during deployments and dev sessions for projects that use declarative schedules.
diff --git a/apps/webapp/app/v3/services/createBackgroundWorker.server.ts b/apps/webapp/app/v3/services/createBackgroundWorker.server.ts
index 43551e849f0..277d2cda5e8 100644
--- a/apps/webapp/app/v3/services/createBackgroundWorker.server.ts
+++ b/apps/webapp/app/v3/services/createBackgroundWorker.server.ts
@@ -775,27 +775,40 @@ export async function syncDeclarativeSchedules(
     },
   });
 
+  const scheduleIdsToDelete: string[] = [];
+  const scheduleIdsToDetachFromEnvironment: string[] = [];
+
   for (const schedule of potentiallyDeletableSchedules) {
     const canDeleteSchedule =
       schedule.instances.length === 0 ||
       schedule.instances.every((instance) => instance.environmentId === environment.id);
 
     if (canDeleteSchedule) {
-      //we can delete schedules with no instances other than ones for the current environment
-      await prisma.taskSchedule.delete({
-        where: {
-          id: schedule.id,
+      scheduleIdsToDelete.push(schedule.id);
+    } else if (schedule.instances.some((instance) => instance.environmentId === environment.id)) {
+      scheduleIdsToDetachFromEnvironment.push(schedule.id);
+    }
+  }
+
+  if (scheduleIdsToDelete.length > 0) {
+    await prisma.taskSchedule.deleteMany({
+      where: {
+        id: {
+          in: scheduleIdsToDelete,
         },
-      });
-    } else {
-      //otherwise we delete the instance (other environments remain untouched)
-      await prisma.taskScheduleInstance.deleteMany({
-        where: {
-          taskScheduleId: schedule.id,
-          environmentId: environment.id,
+      },
+    });
+  }
+
+  if (scheduleIdsToDetachFromEnvironment.length > 0) {
+    await prisma.taskScheduleInstance.deleteMany({
+      where: {
+        taskScheduleId: {
+          in: scheduleIdsToDetachFromEnvironment,
         },
-      });
-    }
+        environmentId: environment.id,
+      },
+    });
   }
 }
 
diff --git a/apps/webapp/test/syncDeclarativeSchedules.test.ts b/apps/webapp/test/syncDeclarativeSchedules.test.ts
new file mode 100644
index 00000000000..6bd6aaa363f
--- /dev/null
+++ b/apps/webapp/test/syncDeclarativeSchedules.test.ts
@@ -0,0 +1,159 @@
+import { containerTest } from "@internal/testcontainers";
+import type { PrismaClient } from "@trigger.dev/database";
+import { describe, expect, vi } from "vitest";
+import type { AuthenticatedEnvironment } from "~/services/apiAuth.server";
+import { syncDeclarativeSchedules } from "~/v3/services/createBackgroundWorker.server";
+
+vi.setConfig({ testTimeout: 60_000 });
+
+type WorkerArg = Parameters<typeof syncDeclarativeSchedules>[1];
+const noWorker = {} as unknown as WorkerArg;
+
+async function seedProjectWithEnvs(prisma: PrismaClient) {
+  const slug = `sds_${Math.random().toString(36).slice(2, 10)}`;
+  const organization = await prisma.organization.create({ data: { title: slug, slug } });
+  const project = await prisma.project.create({
+    data: { name: slug, slug, organizationId: organization.id, externalRef: slug },
+  });
+  const mkEnv = (envSlug: string, type: "PRODUCTION" | "DEVELOPMENT") =>
+    prisma.runtimeEnvironment.create({
+      data: {
+        slug: envSlug,
+        type,
+        projectId: project.id,
+        organizationId: organization.id,
+        apiKey: `tr_${envSlug}_${slug}`,
+        pkApiKey: `pk_${envSlug}_${slug}`,
+        shortcode: `${envSlug[0]}${slug.slice(0, 5)}`,
+      },
+    });
+  const prodEnv = await mkEnv("prod", "PRODUCTION");
+  const devEnv = await mkEnv("dev", "DEVELOPMENT");
+  return { organization, project, prodEnv, devEnv };
+}
+
+function makeDeclarativeSchedule(
+  prisma: PrismaClient,
+  projectId: string,
+  environmentIds: string[],
+  taskIdentifier = "my-task"
+) {
+  return prisma.taskSchedule.create({
+    data: {
+      friendlyId: `sched_${Math.random().toString(36).slice(2, 10)}`,
+      taskIdentifier,
+      projectId,
+      generatorExpression: "0 * * * *",
+      generatorDescription: "every hour",
+      type: "DECLARATIVE",
+      instances: {
+        create: environmentIds.map((environmentId) => ({ environmentId, projectId })),
+      },
+    },
+    include: { instances: true },
+  });
+}
+
+function countingPrisma(prisma: PrismaClient) {
+  const counts = { instanceDeleteMany: 0, scheduleDelete: 0, scheduleDeleteMany: 0 };
+  const client = prisma.$extends({
+    query: {
+      taskScheduleInstance: {
+        deleteMany({ args, query }) {
+          counts.instanceDeleteMany++;
+          return query(args);
+        },
+      },
+      taskSchedule: {
+        delete({ args, query }) {
+          counts.scheduleDelete++;
+          return query(args);
+        },
+        deleteMany({ args, query }) {
+          counts.scheduleDeleteMany++;
+          return query(args);
+        },
+      },
+    },
+  });
+  return { client: client as unknown as PrismaClient, counts };
+}
+
+const asEnv = (env: { id: string; projectId: string; type: string }) =>
+  env as unknown as AuthenticatedEnvironment;
+
+describe("syncDeclarativeSchedules deletion path", () => {
+  containerTest(
+    "does not issue any instance delete when the env owns no instance of the missing schedules",
+    async ({ prisma }) => {
+      const { project, prodEnv, devEnv } = await seedProjectWithEnvs(prisma);
+
+      for (let i = 0; i < 5; i++) {
+        await makeDeclarativeSchedule(prisma, project.id, [prodEnv.id], `task-${i}`);
+      }
+
+      const { client, counts } = countingPrisma(prisma);
+      await syncDeclarativeSchedules([], noWorker, asEnv(devEnv), client);
+
+      expect(counts.instanceDeleteMany).toBe(0);
+      expect(counts.scheduleDelete).toBe(0);
+
+      const remaining = await prisma.taskScheduleInstance.count({
+        where: { projectId: project.id },
+      });
+      expect(remaining).toBe(5);
+    }
+  );
+
+  containerTest(
+    "collapses N per-schedule instance deletes into a single batched deleteMany",
+    async ({ prisma }) => {
+      const { project, prodEnv, devEnv } = await seedProjectWithEnvs(prisma);
+
+      for (let i = 0; i < 5; i++) {
+        await makeDeclarativeSchedule(prisma, project.id, [prodEnv.id, devEnv.id], `task-${i}`);
+      }
+
+      const { client, counts } = countingPrisma(prisma);
+      await syncDeclarativeSchedules([], noWorker, asEnv(devEnv), client);
+
+      expect(counts.instanceDeleteMany).toBe(1);
+
+      const devInstances = await prisma.taskScheduleInstance.count({
+        where: { projectId: project.id, environmentId: devEnv.id },
+      });
+      expect(devInstances).toBe(0);
+
+      const prodInstances = await prisma.taskScheduleInstance.count({
+        where: { projectId: project.id, environmentId: prodEnv.id },
+      });
+      expect(prodInstances).toBe(5);
+
+      const remainingSchedules = await prisma.taskSchedule.count({
+        where: { projectId: project.id },
+      });
+      expect(remainingSchedules).toBe(5);
+    }
+  );
+
+  containerTest(
+    "deletes schedules whose only instance is in the current env",
+    async ({ prisma }) => {
+      const { project, devEnv } = await seedProjectWithEnvs(prisma);
+
+      for (let i = 0; i < 3; i++) {
+        await makeDeclarativeSchedule(prisma, project.id, [devEnv.id], `task-${i}`);
+      }
+
+      const { client } = countingPrisma(prisma);
+      await syncDeclarativeSchedules([], noWorker, asEnv(devEnv), client);
+
+      const schedules = await prisma.taskSchedule.count({ where: { projectId: project.id } });
+      expect(schedules).toBe(0);
+      const instances = await prisma.taskScheduleInstance.count({
+        where: { projectId: project.id },
+      });
+      expect(instances).toBe(0);
+    }
+  );
+});